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Demography Version 4.1 User`s Manual

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1. ON 6 Setting up a Simulation 0 e eee yn toto sine sing Ces VEN PSP E NUI VE UE E Pe Ur a wie EE ET E EU S ee 7 R pnins a Sim latioh mE O 15 WAG WITS TIdcpe T sia 16 Organizing Data and Reporting Results eeeeeeeeeeeeeeeeeeee eene nnn 16 Saving and Opening Problems estote ue irs es ch Pup Re EP win Vr TE EOS e P E e Ere ace E E P NEU sca 17 Qu it na e ELT 17 MENUS AND COMMANDS posicstisxictsncvcceastdcwscietaansectesiocsvececssatecsewaacsuisocarweacsns 18 Fil Men EP nena T E E E OEN S 18 lonia 20 C ntrol MO Th m T T EPM 21 Mni TT T T 24 AJ oY CS ee 25 Windows Menu er a sce R TRIER RE aint sib crore Sesce arate boi Grae wise EE RR ae bce Bala Gg se aaa eae LE Gare saw ened 26 GLOSSARY Fem ccaneeainen sanencensiconantmnueainetnamoctassieeceneaatuentecestacendenetnanehetuatecseteanee 34 APPENDIX 1 HARDWARE AND SOFTWARE REQUIREMENTS 36 I an t Open the Program 5 esed es Neve s Nene sis ea sia pes VR SEO REN E wid US oie ROS EE Fee user VEU sence 37 I Can t Open a Saved Demography Document cceeeeeeeeeeeeeeeeeee eee hehehe 3
2. c ccc ce cece cece ccc e cee c enc en cee he hehehe nnn 71 Demography User s Manual 1 Preface Demography is a simulation of population growth in an age structured population This program allows users to graphically enter age specific fertility and mortality rates for a population enter an age pyramid for an initial population and then observe the changes in population size and in the age distribution through time Demography allows students to ask a variety of what if questions to design and perform their own investigations and to explore the implications of various population policies The direct manipulation graphical interface encourages exploration and makes the program accessible to introductory students Nevertheless the simulation model is capable of addressing problems that even graduate students in population biology sociology geography or environmental studies will find interesting and challenging Demography was developed by the Biology Software Lab at the University of Oregon as part of a curriculum project called Workshop Biology an innovative approach to teaching introductory biology to non majors As with our Workshop Biology course in general Demography is designed to help accomplish three broad goals 1 to help students understand difficult concepts by inviting them to challenge misconceptions and preconceived notions 2 to get students involved in their own scientific investigations and 3 to hel
3. Get an Error Message When Try To Set a Mark If Demography reports an insufficient memory error when you are attempting to create a new mark the problem may be that there is not enough memory for the requested operation Try removing unused marks then save the file If there are other applications currently running try quitting those applications in order to free up memory I m Having Trouble Setting My Graphs Make sure you click on the window first to make it the active window Check to see that the cursor turns from an arrow to a cross shape when you position it over the graph Click on the graph at the point you want to set or hold down the mouse button and drag the graph into the shape you want If you are working with a two sex model first click on the legend before setting points Click on the M for males or the F for females Then click on the points on the graph 38 Demography User s Manual Appendix 3 Notes for Instructors In this section we provide some suggestions for instructors on how to use Demography in the classroom and laboratory First we provide some exercises that instructors can do to help them understand the program and its capabilities Second we describe a series of activities used in laboratory sessions in our general biology class for non majors at the University of Oregon Appendix 4 A Sample Learning Module contains the packet of materials that we hand out to our students Instructors should feel free
4. Rio UEST M ONES IA S D e Library vH Demography Version 4 1 User s Manual Daniel Udovic University of Oregon Gordon Hennesy University of Oregon Will Goodwin University of Oregon Jasper Barber University of Oregon A BioQUEST Library VII Online module published by the BIOQUEST Curriculum Consortium The BIoQUEST Curriculum Consortium 1986 actively supports educators interested in the reform of undergraduate biology and engages in the collaborative development of curricula We encourage the use of simulations databases and tools to construct learning environments where students are able to engage in activities like those of practicing scientists Email bioquest QObeloit edu Website http bioquest org Editorial Staff Editor John R Jungck Managing Editor Ethel D Stanley Associate Editors Sam Donovan Stephen Everse Marion Fass Margaret Waterman Ethel D Stanley Online Editor Amanda Everse Editorial Assistant Sue Risseeuw Beloit College Beloit College BIoQUEST Curriculum Consortium University of Pittsburgh University of Vermont Beloit College Southeast Missouri State University Beloit College BioQUEST Curriculum Consortium Beloit College BIoQUEST Curriculum Consortium Beloit College BioQUEST Curriculum Consortium Editorial Board Ken Brown University of Technology Sydney AU Joyce Cadwallader St Mary of the Woods College Eloise Carter Oxford College Peter Lockhart Massey Universi
5. The display can either be in a graphical form or in tabular form To switch from one to the other click on the table or graph icon in the tool bar above the graph To see this window if it is not already shown choose the Survivorship vs Age command from the Windows menu Current Age Distribution Male Female Displays the percentage of total population or the total number of individuals currently in each age interval males are on the left in blue females are on the right in red Also 30 Demography User s Manual allows you to change the number or percentage of population in each age interval by clicking on the bars of the pyramid and dragging them to where you d like to set the data To switch from percentages to numbers or vice versa click on the or 76 icon in the tool bar above the graph The display can either be in a graphical form or in tabular form To switch from one to the other click on the table or graph icon in the tool bar above the graph You may enter data directly into the table or edit any of the values in the table To see this window if it is not already shown choose the Current Age Distribution command from the Windows menu Population Size vs Time Populations P 0 p u l a t i 0 n Displays the calculated population for each time interval When the population gets large the population values on the y axis will be expressed in scien
6. the next higher bar represents 5 10 years old etc In each age class females are shown in red on a color monitor to the left of the center vertical axis males on the right in blue O current Age Distribution 0 Male Female Figure 3 The Current Age Distribution Window Demography User s Manual 51 The mortality graphs the fertility graphs and the current age distribution can be edited by using the mouse to move points to desired locations To edit a graph first make sure that the window you need to edit is the active window If it is not activate it by placing the mouse anywhere in the window and single clicking Once the window is active note that the cursor changes from an arrow to cross hairs whenever it is in the graphing region Practice clicking and dragging the mouse in the graphing region Notice how the points or bars move to the position of the cursor You may use the mouse to reshape the graphs or bar charts in any way you wish You may also change the fertility and mortality graphs by using the buttons in the tool bar at the top of the window Clicking on the second button from the left HJ will cause all of the values on the graph to be shifted left Clicking on the next button E will cause all values to be shifted right Clicking on the rightmost button LI allows you to multiply all of the y values on the graph by the same amount These graphs can be changed at any time even when a simula
7. 11 Double clicking 11 Dragging 11 Pointing 11 Selecting 11 Marks Notes 27 28 33 44 48 Setting 23 Marks menu Go To 32 Notes 33 Remove 32 33 Set 32 Maximum age 16 31 McFalls Joseph A Jr 44 Mean life expectancy 9 39 41 45 47 51 55 59 Menus Control 22 27 28 29 30 58 Edit 27 28 File 12 24 25 26 27 49 Marks 27 28 32 33 65 Settings 15 21 22 31 37 39 46 57 2 Demography User s Manual Windows 33 35 36 37 38 39 40 57 63 Microprocessor 68K 42 PowerPC 42 Model building 50 Model settings 15 16 39 Models Choosing types 31 Density dependent 17 18 19 20 21 Dispersal 17 18 Female limited 17 Harmonic mean 17 Immigration and emigration 17 Male limited 17 Sex differentiated 16 17 21 33 34 Simple 16 17 33 50 Mortality 55 Age specific 13 38 41 46 51 59 63 68 Infant 47 Open ended investigation 7 47 48 Open ended investigations 68 Percent juvenile 39 40 Population momentum 46 63 68 Population policies China 9 Population Reference Bureau 44 Presentations 46 Printing 24 Problems 43 Quitting 24 Saving 24 Settings menu Display 22 31 Fonts 31 32 Initial Setup 31 Model 15 31 39 Sex ratio 41 Current 40 Primary 33 40 41 Spreadsheet See tables Stable age distribution 38 40 41 47 65 68 Summary statistics Definitions 39 Survivorship curves 36 Table icon 14 Tables 14 S
8. however the actual impact levels off The point at which the graph levels off the asymptote is determined by the total amount of resources available As the size of the population increases and places greater pressure on resources total potential impact increases but actual impact levels off O Actual vs Potential p H 8 Potential Figure 7 The Actual vs Potential Impact Window This window is only accessible when the density dependent model has been chosen from the Model Settings dialog box 4 The model calculates the average amount of resources actually consumed by individuals in each age class using the following formula realized consumption ideal consumption x actual impact potential impact In this version of the program the proportion of ideal consumption actually realized does not depend on age 5 The age specific birth and death rates Figure 8 represent ideal values that would be achieved if realized consumption were equal to ideal consumption The simulation model modifies these values each time interval by taking into consideration the proportion of realized consumption to ideal consumption Thus if population pressure on the resource is high realized consumption will be low relative to ideal consumption and consequently birth rates will be lower and death rates higher In the current version of the program the user does not have control over the relationship between birth and death rates
9. the No button To return to using the current file instead of closing it click on the Cancel button Save To save the file you are currently using choose the Save command from the File menu A window will appear asking you to choose a name and location for the new file Type in a new name and click on the OK button Caution if you have opened a file made changes to it and you want to save these changes to your own file but don t want to change the original file use the Save As command instead Save As To save the file you are currently using under a different name choose the Save As command from the File menu A window will appear asking you to choose a name and location for the new file Type in a new name and click on the OK button The old file will not be affected Page Setup The Page Setup command from the File menu displays a window which shows the current page setup for the printer Choose this command before you choose the Print command to ensure the page setup is the way you want it Print After you have checked the page setup for your printer with the Page Setup command choose the Print command from the File menu to print a view of the windows from Demography in their current state A dialog box will appear asking you to select the windows that you wish to print and how you want them arranged Once you have made your selections click OK The standard Macintosh print dialog box will appear Ch
10. 16 31 Age pyramid 7 9 13 41 47 51 52 54 55 56 Age Pyramid 1 1 47 Age pyramids 47 51 Age structure 51 54 63 64 68 Biology Software Lab 3 7 9 Birth rate Crude 39 41 Control menu Go 29 58 Go For 29 58 Go Until 28 29 58 Reset 27 30 Reset All 27 30 Show Hide Control Panel 22 30 Step 29 30 58 63 Stop 29 30 58 Control Panel 22 30 45 58 Death rate Crude 39 41 Delaying reproduction 47 Dependency ratio 39 40 41 Doubling time 9 21 39 41 47 50 51 55 61 Edit menu Clear 28 Copy 27 Cut 27 Paste 28 Show Hide Clipboard 28 Undo 27 Emigration 17 Epidemics 68 Exponential growth 50 Exporting 23 Fertility 55 Age specific 7 13 16 41 51 61 65 File menu Close 25 New 25 Open 12 24 25 Page Setup 26 Print 24 26 Print Setup 24 Quit 24 27 Index Save 24 26 Save As 24 26 Graph icon 14 15 Graphs Auto scaling 58 Editing 14 34 Rescaling 34 Switching from tables 14 Switching to 34 35 37 38 Hardware requirements 42 Hypothesis 51 59 60 61 62 64 65 66 67 70 71 Immigration 17 Initial values 31 Innate capacity for increase 39 Instructors 7 44 60 62 64 67 Developing presentations 46 Exercises for 45 Preparing learning materials 48 Resources for 44 Intro Tour 55 57 Logistic growth 50 Lutz Wolfgang 44 Macintosh Operating system 42 Macintosh basics Clicking
11. Can you suggest other experiments that could be done to help answer the original question IMPORTANT Before you proceed to the next exercise make sure that you have talked to one of your instructors about your experiment and your results Demography User s Manual 55 Exercise 2 Fertility and Doubling Time The goal of this exercise is to examine how changes in age specific fertility rates influence a population s doubling time Focus on the following task Keeping all other things equal evaluate the relative impact on doubling time of changing the age of first reproduction vs changing the Total Fertility Rate To do this exercise using Demography open the problem file called Exercise 2 1 Before you start making changes to the fertility graph give the above question some thought make an hypothesis and explain your reasoning 2 Design an experiment that could test your hypothesis Describe your design below Please keep in mind that for your experiment to be useful in evaluating your hypothesis you should try to change only one thing at a time If you want suggestions we ll be glad to help but you should feel free to describe your experiment and then go ahead and do it 56 Demography User s Manual 3 Describe your results Graph paper is available if you need it 4 What conclusions can you draw from this experiment Is it consistent with your initial hypothesis If not can you explain why Can you suggest other experimen
12. active If you choose this command while the simulation is running the simulation will immediately stop and then step through one more interval Stop After you choose the Go command the simulation will continue running and the display windows will continue updating until you stop the simulation Choose the Stop command from the Control menu Demography User s Manual 23 The Stop command is inactive and will appear grayed out whenever the simulation is stopped Reset After you start Demography but before you have run the simulation by selecting the Go or Step commands you can set the initial state for the run of the simulation At any time you are running the simulation you may want to return to this initial state The Reset command from the Control menu or the Reset button on the Control Panel will set the population size and age distribution back to their initial values It does not however change the fertility or mortality settings After choosing Reset a window will appear asking you whether you want to save the current state before returning to the initial state If you click Save you will be setting a mark see the Mark menu and you will be asked to give it a name Reset All The Reset All command from the Control menu is similar to Reset In addition to resetting the population size and age distribution however Reset All resets the fertility and mortality values to the values selected before you ran the
13. cut copy and paste Windows Menu Fertility vs Age Mortality vs Age Survivorship vs Age Current Age Distribution Population Size vs Time Stable Age Distribution Summary Statistics The commands under the Windows menu display Demography windows These commands cause the windows to appear if they are not already being shown The Primary Sex Ratio command allows you to change the sex ratio at birth in the sex differentiated model i e ratio between male and female offspring If the simple model is running this command appears grayed out and is inactive Demography User s Manual 27 You may enter data in three windows Fertility vs Age Mortality vs Age and Current Age Distribution You have the option in each of these three windows of entering values graphically or in tabular form All other windows display values calculated based on these and other values such as the Demography parameters To switch to the table view click on the table icon in the tool bar at the top of the graph The graph will be replaced by a spreadsheet like table Click on the cell you want to change and enter the value To go back to the graph view click on the graph icon L_J in the tool bar at the top of the graph To enter data graphically just click on the point on the graph where you want to set a data point Or you can hold down the mouse button and drag the line or pyramid into the shape you want Note if you are u
14. from the clipboard and paste it into a Notes Window associated with a mark see the Marks menu The Paste command is only active when the cursor is positioned within an active Notes Window and there is text on the clipboard Clear Use the Clear command from the Edit menu to delete selected text from the Notes Window associated with a mark see the Marks menu The selected text will be removed from the notes It will not be placed on the clipboard The Clear command is only active when the Notes Window is active and some text has been selected Show Hide Clipboard The Show Hide Clipboard command from the Edit menu presents or hides a window which displays the current contents of the Macintosh clipboard Control Menu Settings Mark Go Until gt Go For gt Go 366 Step 36E Stop a6 Reset R Reset All Hide Control Panel 3T Go Until To run a simulation until a specified time period choose the Go Until command from the Control menu A hierarchical menu will appear giving you several choices for ending times If you wish to specify a number that doesn t appear in the menu choose Custom A dialog box will appear asking you to specify the ending time The simulation will run until it reaches the time period you specify and then stop automatically 22 Demography User s Manual The Go Until command is inactive except when the simulation is stopped and will appear grayed out whenever the s
15. last simulation After choosing Reset All a window will appear asking you whether you want to save the current state before returning to the initial state If you click Save you will be setting a mark see the Mark menu and you will be asked to give it a name Show Hide Control Panel The Control Panel is a window that contains four buttons one for each of the four commands above Stop Go Step and Reset The Control Panel provides an easy and convenient way to run simulations It always appears in front of other Demography windows Occasionally you might find it useful to hide the Control Panel You may do this either by clicking in the panel s close box or by choosing Hide Control Panel from the Control menu When the panel is hidden you may choose Show Control Panel from the Control menu to bring it back into view 24 Demography User s Manual Settings Menu Marks Model Display Initial Setup gt Font Size Model Choose the Model command from the Settings menu to change the following settings prior to any run of the simulation e Maximum Age Click on the space next to Maximum Age Enter a number that represents the maximum age an individual can reach in this population Length of each age interval Click on the space next to Length of each age interval Enter a number which can divide the maximum age evenly Immigration Emigration Click on the checkbox next
16. or steady state called the Carrying Capacity K In their simplest form both of these models assume that there is no variation within a population in birth or death rates Nature of course is not so simple Birth rates and death rates are influenced by a wide variety of factors many of which are constantly changing What then is the point of these simple models First making a model forces us to clearly identify the features of interest and to carefully figure out how to quantify them Second a simple model is a place to start We can build models of complex systems but unless we start with simple models and gradually make them more complex we can never hope to understand why our models behave the way they do If we don t understand them we are not likely to have much confidence that the crucial features of our model accurately reflect the real world So exponential and logistic growth provide a starting point for understanding population processes Simple concepts such as Doubling Time and Carrying Capacity can be very useful in thinking about major population trends Demography is a computer simulation model that allows you to go beyond the simple models of population growth by examining population models that allow mortality and fertility to change with age and sex Studying models of this sort will allow us to examine several important features about the growth of natural populations including humans Some of these features hav
17. population momentum for a region with a rapidly growing population That is assume a new policy is implemented that reduces the Total Fertility Rate to replacement levels about 2 0 but it will depend on the mortality function Starting with an initial age distribution that reflects the current situation manipulate the fertility curve to model the new policy Examine how the age structure and population size change with time 11 Study the impact of a hypothetical or real epidemic on population age structure and population growth for a particular region of the world You will have to make assumptions about the affects of the epidemic on age specific mortality rates You might start by letting your population reach a stable age distribution and then change mortality rates to reflect the spread of the epidemic Demography User s Manual 41 How We Use Demography at the University of Oregon By the time we use the learning module in Appendix 4 our non major students have already been introduced to exponential and logistic growth have seen one or two videos relating to population issues and are working in groups researching human population issues The first activity in this module Part 1 is a tactile exercise that introduces students to age pyramid diagrams by having them construct them with construction paper and see how they change through time given simple rules for mortality and fertility Age Pyramid 1 1 a companion computer progra
18. specified as the percentage of each age group leaving the population during each time interval The emigration rates shown in the graph in Figure 5 would be very high since more than 20 of each age group would be leaving during each time interval The model adds the number of individuals immigrating into each age group before birth and death calculations are made The number of individuals emigrating from each age group are subtracted from the population after immigration is added but before birth and death calculations are made 12 Demography User s Manual The statistics presented in the Summary Statistics Window and the calculation of the stable age distribution assume no immigration or emigration even when these features are enabled Consequently the stable age distribution actually achieved in a simulation allowing immigration and emigration may differ significantly from the pyramid presented in the Stable Age Distribution Window The differences can be used as an estimate of the effects of dispersal on the population Density Dependent Model Another new feature in Demography 4 1 is the ability to model density dependent growth in age structured populations If you want to use a density dependent model click on the appropriate button in the Model Settings dialog box The density dependent model we have chosen focuses on the consumption of a single potentially limiting resource and includes the following steps 1 An ideal c
19. t t i 0 600 a 0 600 l l 0 400 0 400 t t y 0 200 y 0 200 0 000 0 000 0 50 100 0 50 100 Age Age 2 Entering Your Data Find the file entitled Exploring Demography on your computer and double click on it Once Demography starts up and the file is displayed on your screen enter your mortality and fertility predictions in the graphs displayed on the screen You can manipulate the graphs by clicking and dragging on any of the points Notice that as you change the fertility and mortality graphs the values for doubling time total fertility and life expectancy are automatically adjusted How do the values obtained compare with those predicted Enter the observed values in the table on the previous page If there are major discrepancies what kinds of adjustments do you need to make in your predictions Adjust the graphs until you feel the graphs and the summary statistics match with your understanding of the global population 70 Demography User s Manual 3 How Will the Age Distribution Change Through Time Note the age structure graph Suppose that the population grew based on the values for fertility and mortality that you have entered What do you think the shape of the age distribution would be like in 100 years Draw your prediction on the graph to the left below Predicted Observed 100 100 80 80 60 60 A A I 40 7 40 e e 20 20 0 0 Female Male Female Male You can test your prediction by running the simula
20. to modify these materials to suit their needs Finally we describe how instructors can take advantage of some of Demography s features to help prepare learning materials Some Resources Instructors wishing to improve their background in demography can find good introductions in most ecology textbooks To get a better handle on issues in human demography two publications from the Population Reference Bureau PRB provide short introductions McFalls Joseph A Jr 1991 Population a lively introduction Population Bulletin 46 2 1 43 Lutz Wolfgang 1994 The future of world population Population Bulletin 49 1 1 47 PRB also publishes a very useful annual global data sheet in poster format electronic versions are also available For World Wide Web resources see the PRB home page http www prb org prb and PRB s PopNET http www popnet org e the U S Census Bureau s home page http www census gov and their excellent international page http www census gov ftp pub ipc www e the United Nations Population Information Network home page http www undp org popin popin htm and the University of Oregon s Population Page http yucca uoregon edu popinfo The latter page will maintain useful information on how to use Demography as a learning tool and provides access to Java Demography a version of this program that can be run through any computer with a Java savvy web browser e g N
21. values are for doubling time total fertility rate and life expectancy for the world population Definition Your Estimate Observed Value based on your fertility and mortality graphs Total Ave number of offspring Fertility per female over her Rate lifetime if she lived through reproductive years Life How long an individual Expectancy can be expected to live on average Doubling The time it would take a Time population to double given no changes in age specific mortality or fertility rates For most populations including humans birth rates fertility and death rates mortality vary with age Using the graphs on the next page draw your predictions of what fertility and mortality functions should look like To do this divide the population into age categories using 5 year intervals 0 5 5 10 10 15 etc Demography User s Manual 69 On the Fertility vs Age graph chart the average number of offspring per individual during each 5 year interval For example suppose that the average individual has 0 5 offspring between the ages of 50 and 55 Then you would enter a fertility rate of 0 5 for age 50 On the Mortality vs Age graph plot the proportion of individuals in a given age category that can be expected to die during that interval For example if you feel that the probability of dying between ages 50 and 55 is 20 then you would enter a mortality rate of 0 2 for age 50 F 1000 M 1000 e o r 0 800 r 0 800
22. will appear with the text Please enter a name for the mark A name will already be there Mark at time 5 for example where 5 would be the 5th year in the run of the simulation You may move your mouse to click on this space and type in a new name When you are finished entering the name of the mark click on the OK button or press the Return or Enter key on your keyboard If you decide you don t want to set the mark use your mouse to click on the Cancel button in the dialog box Go To After you have set a mark in a run of the simulation you can restore the run of the simulation to the state it was in when you set the mark Move the cursor over the Marks menu press the mouse button and drag the cursor down until Go To is highlighted but don t release it yet Now drag the cursor to the right until you can see the names of the marks Drag down until the mark name you want is highlighted then release the mouse button Before the program goes to the mark it will ask you whether you want to save the current state of the simulation the state before you go to the mark If you click on the Save button it is the same as placing a mark at the current state of the simulation before going to the mark In fact the mark it places is called Current state at n where n is the number of the current time before the simulation goes to the mark The current state mark will show up in the Go to and Remove lists so you can
23. would have in her lifetime on average if she lived through her reproductive years 46 Demography User s Manual Part 1 Constructing Age Pyramids In this activity you will be using construction paper to construct age pyramid diagrams for populations Each piece of construction paper represents a different age group Notice that the population is divided into males and females You will be able to watch what happens as time goes by and each age group gets older Exercise 1 With the pieces of construction paper make an age distribution graph for a hypothetical population for example the population of Sweden as shown in on p 847 of The Nature of Life by Postlethwait and Hopson 3rd edition McGraw Hill How many years are there in each age category Measure how many people are in each category using the scale at the bottom of the age pyramid 0 10 51 60 11 20 61 70 21 30 71 80 31 40 81 90 41 50 91 100 Why do you think this age distribution is shaped like a pyramid Demography User s Manual 47 Now we are going to look at what happens as time goes by Leap ahead 10 years For some reason our hypothetical population is not reproducing any more Furthermore there is 100 survival until age 100 There is 100 mortality at age 100 Remove everyone in the age 91 100 category and move all of the other categories up ten years Are there any people in the age category of 0 10 years Why or why not Repeat this for 90 more ye
24. 6 Demography User s Manual Appendix 1 Hardware and Software Requirements Demography is designed to operate best on the Macintosh II family of computers or on Power Macintoshes However it will run nicely though slower on lower end models on Macintoshes of any type so long as at least 1 megabyte is available to the program However for a large run with many marks it may be necessary to set the partition size for Demography to more than 1 megabyte Choose Get Info from the Finder In order to run the program you only need to have the application itself All of the resources that the program requires are already installed in the application Of course if you have saved an experiment and want to open it you will need to have the file into which you saved that experiment Summary of Hardware and Software Requirements Macintosh computer with at least 1 megabyte of available random access memory RAM Macintosh operating system 6 x or greater is required However system 7 x or Mac OS 8 0 is recommended e Demography 4 1 is accelerated for running on computers with PowerPC microprocessors Three versions of the program are available a 68K version which will run in emulation mode on PowerPC computers a PowerPC only version and a fat binary version which automatically runs the version of the application best suited to your computer but takes up more disk space e Demography application installed on the hard disk or a floppy di
25. 7 I Get an Error Message When I Try To Set a Mark ceeeeeeeeeeeee nennen rne 37 I m Having Trouble Setting My Graphs ccccee cece cece cee e cence eee e en cee hne 37 APPENDIX 3 NOTES FOR INSTRUCTORG 0 0cecececeeeeeceeeeeeeeeseeeeeeeeeeeeeeees 38 Some R so rc s iu ee esae saad ue a ERA VA EE AREE VAPEUR A REEAVA MEE ER EER VAR U VAR EAVAREE EA EE EAR ees 38 Exploring Demography Some Exercises for Instructors eeeeeeeeeeeeeeeeeeeee nennen 39 How We Use Demography at the University of Oregon eeeeeeeeeeeeeee e ee heh hn 41 Using Demography s Features To Prepare Learning Materials cccecccccccccceccecceceeceecs 42 APPENDIX 4 POPULATION MODELING SAMPLE LEARNING MODULE 1 44 Tri OMU COON PEUT 44 OVORVICW ecse dsc adis o3 Rau aa Pea wol ana liv sii ss i Pead ls s sad Cobden ERR A PIN a RIPI ead goadse se 45 Part 1 Constructing Age Pyramids cccccc cee ce cece enc ee cee eene hehehe hse e nnn 46 Part 2 Exercises in Demography ccccccceccccccccecceceecen hehehe hehehe sr hens 49 Part 3 Independent Investigations and Presentations ceceecce cece ccncencescescescesseceeees 63 APPENDIX 5 EXPLORING DEMOGRAPHY SAMPLE LEARNING MODULE 2 67 T troducti n a 5555 rU 67 Activity I Issues in Human Population Growth 0 ccc cece cece ccc e cece cece cence ececeeeescesceecs 68 Activity II Stable Age Pyramids
26. Fertility vs Age Mortality vs Age Summary Statistics Survivorship vs Age Current Age Distribution and Population Size 2 Certain windows can be directly manipulated Others cannot Experiment to determine which windows can be manipulated and how you can manipulate them Understanding Some Fundamental Concepts 3 What is the meaning of each of the terms in the Summary Statistics Window Systematically determine which summary statistics are influenced by changes in those graphs that are editable In each case can you explain why For example why don t changes in the fertility graph cause changes in Mean Life Expectancy 4 For at least some of the cases in which changes to a graph do cause changes in a summary statistic or in another graph investigate the nature of the relationship For example how would you describe the relationship between age specific mortality and life expectancy Given your understanding of this relationship could you predict which age group s mortality rate has the biggest impact on life expectancy Can you design and conduct a set of experiments to test your prediction 5 Use the Control Panel to step through a simulation You will be watching the age pyramid of the population change through time Experiment with different fertility and 40 Demography User s Manual mortality rates and different initial age distributions to see how they affect the way the age distribution changes with time Do you observe ch
27. The exercises in the sample teaching module illustrate ways to use the program as a learning tool In this section we describe how to start the program open files enter population data either graphically or in spreadsheet format run simulations organize your findings save your simulations in a file and quit the program Running Demography In order to run Demography first make sure it is installed on your computer s hard disk or on a floppy disk that you have inserted into the disk drive The Demography application icon looks like this Demography 4 1 Make sure that you also have all the problem files that you will need if any check with your instructor to find out what they are called They will look like the icon below of course the names will be different Note that this type of icon a document icon differs from the application icon It looks like a piece of paper with the top edge bent over China 2000 Double click on the Demography application icon The program will start up Opening a Problem To open a problem file choose the Open command from the File menu If it is grayed out it means you already have a file open so you must close it before opening a new one To close the file choose the Close command from the File menu You will see a window with names of different files Find the problem file name and click on it to select it then click on the button marked Open or double click on the prob
28. and consumption Look for this feature in the next version 14 Demography User s Manual AS Birth amp Death vs Age Figure 8 When using the density dependent model chosen from the Model Settings dialog box the mortality and fertility curves are combined in one window Select either the B or D in the figure legend to enable changes to that particular curve The values in the curve represent ideal values for birth and death rates that are achieved only when realized consumption equals potential consumption Variable Settings By choosing the Variables command from the Settings menu users can modify the values for the initial time and for the current population size For example if you wanted to model the growth of the U S population since the turn of the century you might want to set initial time to 1900 and the population size to 76 million In the sex differentiated models you can also set the primary sex ratio This relates to the ratio of the number of male offspring produced per female offspring This is reported in the Summary Statistics Window when a sex differentiated model is running In addition to the primary sex ratio which you set there is an additional parameter current sex ratio which is calculated This relates the number of male and female individuals within the population It is reported in the Summary Statistics Window You can modify this value indirectly by manipulating the graph
29. anges that you don t understand or that appear counterintuitive How should you go about resolving such conflicts HINT Construct hypotheses that might explain the differences between what you expected and what you observed make predictions based on your hypotheses and design and conduct controlled experiments to test them Using Advanced Features 6 Using features from the Settings menu set up a model to study the demography of a bird population in which the birds live a maximum of 10 years or a population of fish that live for only a few years but have very high fertility values 7 Using one of the sex differentiated models available from the Settings menu set up a model to study the impact of differential abortion rates or infant mortality rates based on gender e g female fetuses are aborted more frequently in China and infant mortality rates are higher for females Conducting Investigations Developing Presentations and Activities Several of the following problems are taken from the learning module in Appendix 4 8 What is the meaning of the stable age distribution graph Construct a set of simulations which demonstrate this concept HINT You can use Demography s marking features to help develop a presentation 9 Use Demography to develop a presentation that illustrates the relationship between age specific mortality and fertility rates and the stable age distribution of a population 10 Study the implications of
30. aphy User s Manual Viewing Results The results of simulation runs are presented in two windows Population Size vs Time and Current Age Distribution These windows are updated every time interval If you watch the graph of population size as the simulation runs you will notice that it automatically rescales whenever necessary It may take you several runs to get used to the unexpected sudden changes in the shape of this graph that occur during rescaling Organizing Data and Reporting Results Marking The Mark feature allows you to set a mark at any particular time interval during the run of a simulation You can enter a meaningful name for the mark to help you understand remember why that particular time interval was important You can then enter notes see page 23 to keep track of information in association with the mark When you set a mark Demography saves all the values displayed in the windows as well as the position of the windows on the screen This allows you to come back to this point and even to start the simulation running again from that point if you wish Marks allow you to summarize a simulation run or a set of runs If you want to show someone what happens to a population at various times instead of running the simulation and stopping it whenever you want to point something out you can do the run beforehand and set a mark at each time interval of interest This can save a lot of time especially if the time inter
31. ar in these windows refer to Menus and Commands Windows to the Glossary or to a relevant textbook Manipulating Population Characteristics The mortality graphs the fertility graphs and the current age distribution can be edited by users There are three ways to change the graphs by using the mouse to move points to desired locations by typing in values in a spreadsheet format or in the case of mortality and fertility by clicking on the buttons on the tool bar at the top of the window to manipulate the whole graph e g shifting all values to the right or left or multiplying all y values by a constant To edit the graph directly first make sure that the window you need to edit is the active window If it is not activate it by placing the mouse anywhere in the window and single clicking Once the window is active note that the cursor changes from an arrow to cross hairs whenever it is in the graphing region Practice clicking and dragging the mouse in the graphing region Notice how the points or bars move to the position of the cursor You may use the mouse to reshape the graphs or bar charts in any way you wish To help you to position points on the graph with precision note that the current position of the cursor appears in the tool bar at the top of the window If you wish to be even more precise you may enter data in a spreadsheet format Click on the table icon on the tool bar at the top of the window The graphical
32. ars moving the age classes every ten years Record your observations of how the age distribution changes Initial After 40 years After 80 years Explain the changes in the shape of the age distribution pyramid that you observed 48 Demography User s Manual Exercise 2 Now we are ready to look at a more realistic population Set up your population pyramid again This time there will be 25 mortality one fourth of the people die in each age group Beam ahead 10 years For each age group you will have to subtract a quarter of the population before they move up an age category Do this using the scale at the bottom of the age structure Next we will calculate births for the population For this example we will assume that only individuals between 21 and 30 are producing offspring and that on average individuals in this age group produce three offspring during the 10 year interval Measure how many people are in the age category 21 30 years and calculate the total number of births during the 10 year period Number of people 21 30 X3 children in the 0 10 age group Cut a piece of paper to fill in the 0 10 age group based on the number of births Repeat this for 40 more years recalculating the classes every 10 years Describe how this age pyramid looks compared to the first age pyramid you constructed Initial After 20 years After 50 years What would you predict would happen in 100 years Demography User s Manual 49 Part 2 E
33. can see them all 1 the Mortality vs Age Window 2 the Fertility vs Age Window 3 the Current Age Distribution Window and 4 the Statistics Window labeled Exercise 3 You may occasionally wish to check the Population Size vs Time Window as well to see this window select the Population Size vs Time command from the Windows menu Manipulate the current age distribution graph so that it looks like the one in Figure 5a 3 00 0 3 00 Trial a Trial a Trial a Initial 25 years 50 years Figure 5 How a population s age structure changes with time 58 Demography User s Manual Now select Step several times to see how the shape of the age distribution changes After 25 years 5 steps what does your distribution look like Fill in Figure 5b After 50 years 10 steps Fill in Figure 5c 1 Explain your results Now select Go from the Control menu The simulation will continue until you select Stop from the Control menu Each time the screen updates another 5 year interval has passed Allow the simulation to run until you can no longer detect change in the age distribution Stop the simulation and record your findings in Figure 7 a on the next page Repeat this experiment two more times with different initial age distributions Record your initial distributions in Figure 6 Do not change the mortality or fertility graphs Remember the idea of this experiment is to keep everything else the same and just change the i
34. d by the total current population Primary Sex Ratio Sex differentiated model only Primary sex ratio is entered using the Initial Setup command under the Settings menu It is reported as the percentage of female offspring of total offspring produced 34 Demography User s Manual Glossary Below are some of the key terms used in Demography and in this manual Age Distribution The proportion of individuals in a population in age each class Typically displayed in a modified bar chart called an age pyramid Age Specific Fertility Rate The number of births per individual within a specific age interval during a specified time Age Specific Mortality Rate The fraction of individuals in a population that die during a given age interval For example if the probability of dying between age 5 and 10 is 0 25 or 25 that would be the mortality rate for that age class Crude Birth Rate The number of individuals per thousand in the population born during a time interval For example crude birth rates for the human are generally in the range from 10 per 1000 per year to 40 per 1000 per year Crude Death Rate The number of individuals per thousand in the population dying during a time interval For example crude death rates for the human population generally range from 5 per 1000 per year to 25 per 1000 per year Density Dependence A form of population growth in which the birth rates and or death rates per individual depend on the s
35. display is now replaced by a table Figure 2 Click in the cell s that you want to change and type in the desired value s To return to the graphical display click the graph icon on the tool bar at the top of the window Demography User s Manual 9 Fertility vs fige Figure 2 The spreadsheet view of the Fertility vs Age Window Clicking on the graph icon in the upper left corner of the window returns you to the graph view Model Settings Some of Demography s settings are under user control By choosing the Model command from the Settings menu for example the user can alter a population s maximum age and the length of each age interval The default settings are useful for human populations By altering these settings as needed users of Demography can study the dynamics of a large variety of animal and plant populations Warning changing these parameters during the run will cause the run to start over from the beginning time interval so only change these parameters before you begin a simulation or when you are ready to start a new one Model Settings Age Interval Maximum Age Rge ranges for used in calculating dependency ratio juvenile ratio Juveniles 0 to 15 Seniors 65 to Man fige see above Immigration Emigration Model Types amp simple fertility mortality not differentiated by sex Seu differentiated models O female limited fertility mal
36. e perhaps as a result of what you have done so far in this activity or as a result of your issues research or from other work in this class Some Possible Topics 1 Study the implications of population momentum for a region with a rapidly growing population That is assume a new policy is implemented that reduces the Total Fertility Rate to replacement levels about 2 0 but it will depend on the mortality function Starting with an initial age distribution that reflects the current situation manipulate the fertility curve to model the new policy Examine how the age structure and population size change with time 2 Study the impact of a hypothetical or real epidemic on population age structure and population growth for a particular region of the world You will have to make assumptions about the effects of the epidemic on age specific mortality rates You might start by letting your population reach a stable age distribution and then change mortality rates to reflect the spread of the epidemic 3 Model the demographics of a primitive society or culture like the hunter gatherers discussed in The Nature of Life and in Race to Save the Planet How might age structure and population size be influenced by the introduction of modern technology and modern medicine Some Suggestions on How To Proceed Think small This is not meant to be a large scale project You will probably spend more time thinking about what question you want to in
37. e construction paper exercises take about one hour and are done in the first lab The structured exercises using Demography are done in the second period They generally take between one and one half and two hours Groups that finish early are encouraged to start their investigation Students who do not complete the activities in the time provided are encouraged to complete the activities outside of class The third period is devoted to investigations and presentations The amount of time devoted to presentations varies depending on class size and the time needed for investigations Since our students have other opportunities to give oral presentations we are not concerned that every group present their findings Using Demography s Features To Prepare Learning Materials Demography can be used to create custom files for problem sets exams or classroom demonstrations The steps involved in creating custom files changing parameters and settings marking saving files are no different than those to use the program and hence all of the relevant program features are described in the manual Here we provide a few pointers that you might find useful Setting marks can be a powerful tool in creating presentations and problem sets Marks allow you to set parameter values exactly the way that you want them position and size windows to suit your needs give those settings an appropriate name and add comments in the associated Notes Window By setting up
38. e limited fertility Q harmonic mean fertility density dependent Cancel OK Figure 3 The Model Settings dialog box allows you to edit settings for the simulation Length of each age interval is the number of years of age between groups of the population It is initially set to 5 years of age which means that the first group will be 10 Demography User s Manual individuals between birth and 5 years old the second group will be individuals between 5 and 10 years old etc up to the age interval between 95 and 100 years Maximum age is the oldest age an individual in the population will reach It is initially set to 100 years old Simple vs Sex Differentiated Models Users may also choose between four different types of population models available in Demography The first which we refer to as the simple model assumes that the organisms are asexual that both sexes are equally abundant and have identical fertility curves and mortality curves or that information about only one sex females is sufficient to determine population dynamics The other three models all allow for differences between sexes in age specific fertility mortality and abundance They differ in the way male and female fertility values are combined to determine actual births see discussion below Unless you are investigating questions that deal specifically with differences between sexes we recommend that you use the simple model It is faster and the
39. e significant implications for population policy As we explore these models we can begin to make sense of real world phenomena even though the models are not perfect representations of reality Simple models let us focus on just a few important features As we gradually add complexity to our models we can then focus on the new features By changing one thing at a time and seeing what effect it has on the outcome we can build up an understanding of complex systems Demography User s Manual 45 Overview This activity will be spread over at least three class periods In the first period you will work in small groups with construction paper to build graphical models age pyramids showing how the age structure of hypothetical populations changes through time We hope that this tactile exercise will give you a concrete feeling for how age pyramids are constructed and how they change through time In the second period you will work with a computer program called Demography This program allows you to graphically enter age specific fertility and mortality rates for a population enter an age pyramid for an initial population and then observe the changes in population size and in the age pyramid through time Structured exercises will help you learn how to use the program and to learn some key concepts about population growth Once you have completed the structured exercises you will design and conduct some modeling experiments of your own Fo
40. e stable age pyramids that differ in shape In fact the stable age distribution for a population can be determined solely from its fertility and mortality functions You can use Demography to help convince you of this if you are skeptical Consider the shapes of the following age pyramids Your task in this activity is to construct fertility and mortality curves that will produce each of these pyramids Some are easy some challenging As you do the activity you should develop predictive hypotheses to explain why certain fertility and mortality combinations yield particular shapes for the stable age distribution S 10 S 10 S 10 t t t a a a b 80 b 80 b 80 l l e e e 60 60 60 A A A 40 40 3 40 e D 20 2 39 D 20 i i i s s s to to to 0 20 0 00 0 20 0 04 0 00 0 04 0 04 0 00 0 04 Female Male Female Male Female Male a Eiffel Tower b Cow Bell c Tombstone 5 1o S 10 t a a b 80 b 80 l l e e 60 60 A A 9 40 40 D 20 D 20 i i s s to to 0 20 0 00 0 20 0 04 0 00 0 04 0 05 0 00 0 05 Female Male Female Male Female Male d Thumbtack e Mummy f Vase c10 u F 80 E 60 B e 40 D i S220 t 0 ig 8 0 05 0 00 0 05 30 00 0 00 30 00 0 05 0 00 0 05 Female Male Female Male Female Male g Taj Mahal h Football i Tornado 72 Demography User s Manual Acknowledgments 8 Age distribution 41 Current 13 14 17 21 22 23 34 36 37 55 56 57 58 63 Stable 14 38 40 57 58 65 Age intervals
41. ee the Workshop Biology home page on the World Wide Web http Biology uoregon edu Biology WWW Workshop biol wb html 2 Demography User s Manual Acknowledgments Workshop Biology has been developed through grants from the Department of Education FIPSE P116A1 0385 and P116A4 1049 and the National Science Foundation USE 9150760 and DUE 9455145 These grants plus a grant from the Howard Hughes Medical Institute have supported the development of Demography and related materials We would like to thank those faculty and students who have tested earlier versions of Demography for their feedback and support and their patience and G Z Brown and his co workers for stimulating discussions regarding program design The staff of the Workshop Biology Project past and present John Postlethwait Alan Dickman Peter Wetherwax Deborah Morris Stacey Kiser and Nan Perigo and participants in our Biology Education Journal Club over the past several years have contributed many ideas about teaching and learning that have influenced our software tools and the curricular materials that use these tools Finally we d like to thank the staff of the BioQUEST Consortium for their continued support of our development efforts Demography User s Manual An Overview of Demography Why are human populations in Africa growing so rapidly even though life expectancy is shorter than in most other parts of the world Why do rapidly growing population
42. enu Summary Statistics Exercise 1 Summary Statistics Current Time 40 Doubling Time 23 24 Mean Life Expectancy 66 44 Total Fertility Rate 3 54 32 Demography User s Manual The Summary Statistics Window presents values related to the population s growth These composite values are calculated from the values which are entered in the other windows you cannot change these values directly To see the Summary Statistics Window if it is not already shown choose the Summary Statistics command from the Windows menu The title that appears in the top bar of the Summary Statistics Window is the name of the current open file If you are working with a new unsaved file Untitled will appear You can select the statistics that will be displayed by choosing Display Settings from the Settings menu and checking the appropriate boxes in the Display Settings dialog box The following are the values that can be displayed in this window Doubling Time How many years it would take for the population to double or halve if the value is negative Innate Capacity for Increase A measure of the capacity for the population to grow or shrink if negative Mean Life Expectancy The average age to which an individual can be expected to survive Total Fertility Rate The total number of offspring a female would have on average if she were to live to the maximum age Crude Birth Rate The number of individuals per thou
43. ertility and mortality rates in particular how is it related to the rate of growth of the population 1 Before you start experimenting give the above questions some thought make a hypothesis and explain your reasoning To do this exercise using Demography open the problem file called Exercise 4 Notice that you now see five windows You will need to look at most of the available windows at various stages in this exercise so you will have to get used to moving windows around on your screen so that you can see the one that you want The four most important are Mortality vs Age Fertility vs Age Statistics and one window that we have not yet used Stable Age Distribution In this exercise since you will be making comparisons of populations with different mortality and fertility curves Demography s marking feature may be useful Marks allow you to save the state of the population at any time then later come back to that state For example you can run a simulation for 100 time units set a mark then reset the model change the fertility or mortality curves or the initial age distribution again run the simulation for 100 years and set another mark You can then choose the Go to command from the Marks menu to go back and forth between those two sets of windows and compare their values To set a mark delete a mark or go to a mark choose the appropriate command from the Marks menu If you want more detailed information about marking
44. es are used to calculate the number of births The female limited and male limited models assume that births can be calculated directly from the fertility values of the limiting sex For instance if it is generally safe to assume that adding more males to a population would have little effect on births then a female limited model would be appropriate The harmonic mean model is the most complex Rather than assuming that the same sex is always limiting it takes the harmonic mean of the total fertility values for males and females weighted by their relative abundance In this model the number of births in a given time interval will be influenced most heavily by the rarer sex Immigration Emigration Demography 4 1 can now incorporate age specific immigration and emigration into and out of a population If you want to enable immigration and or emigration check the appropriate boxes in the Model Settings dialog box Immigration and or emigration can be incorporated into the simple sex differentiated or density dependent models 8 O Sage vs Emigration gt E EH gt Age vs Immigration Figure 5 The Age vs Immigration and Age vs Emigration Windows These windows are only accessible if they have been enabled by checking the appropriate box in the Model Settings dialog box Immigration is specified as the numbers of individuals per age range who immigrate into the population during a time interval Emigration is
45. etscape 3 0 Internet Explorer 3 0 Demography User s Manual 39 Exploring Demography Some Exercises for Instructors The exercises below range from fairly prescriptive to very open ended You should choose the exercises that you wish to do based on your background experience and interests The first two exercises are designed to help you learn the basic capabilities of Demography and how Demography works Exercises 3 through 5 explore some of the basic terms and concepts of demography They are designed to help develop a deep qualitative understanding of concepts that are generally presented superficially in introductory courses At the same time the exercises introduce other features of Demography Exercises 6 and 7 introduce other advanced features of Demography and demonstrate how the program can be customized for different populations The remaining exercises can be viewed in two ways First each is an open ended investigation of the sort that students might do in an inquiry based lab Second each is an exercise in how to use Demography to present ideas e g students presenting the results of their investigations faculty presenting tough concepts or ideas in a lecture setting These are meant to be examples We encourage you to develop your own investigations presentations How Demography Works 1 Learn what is displayed in each program window Describe briefly but precisely what is displayed in each of the following windows
46. f the mortality rate of age interval 30 35 is 2576 and the number of individuals in that age group at time 10 is 200 then the number of individuals in the age interval 35 40 at time 15 will be 150 s jE Mortality vs Age Figure 1 The Mortality vs Age Window Mortality rates y axis as a function of age x axis In this example mortality rates are low for young ages and accelerate rapidly after age 75 The current position of the cursor is shown in the box on the right hand side of the tool bar at the top of the window 50 Demography User s Manual The values displayed in the Fertility vs Age Window Figure 2 are a measure of the number of offspring that individuals in this age interval will produce during that interval 0S Fertility vs Age F e r t i I i t y Figure 2 The Fertility vs Age Window Fertility rates y axis as a function of age x axis In this example fertility values are displayed for each five unit interval If this represented a human population the units would be years In this example average fertility rates are near zero until age 15 peak at around 35 and then decline again reaching zero by age 60 The Current Age Distribution Window Figure 3 displays the percentage of the total population in each age interval in the form of an age pyramid For instance the lowest bar on the pyramid represents the percentage of individuals in the youngest age interval e g 0 5
47. form To switch from one to the other click on the table or graph icon in the tool bar above the graph To see this window if it is not already shown choose the Fertility vs Age command from the Windows menu Mortality vs Age s m Mortality vs Rge Displays the probability that an individual from any age interval will die during the current time interval Also allows you to change these values by clicking on the points you wish to set by dragging the curve into the shape you want or by clicking on the buttons in the tool bar at the top of the window The button on the left shifts the graph to the left The center button shifts the graph to the right The button on the right allows you to multiply all values on the y axis by a constant amount The display can either be in a graphical form or in tabular form To switch from one to the other click on the table or graph icon in the tool bar above the graph To see this window if it is not already shown choose the Mortality vs Age command from the Windows menu Demography User s Manual 29 Survivorship vs Age survival vs Age SEE S 1 888 u r uU i 8 588 u a I 8 8 58 fige Displays the probability that an individual will survive from age zero to a given age The values displayed are calculated from the mortality values you cannot change this window directly Notice that survivorship curves are decreasing or at least non increasing functions of age
48. hy are human populations in Africa growing so rapidly even though life expectancy is shorter than in most other parts of the world Why do rapidly growing populations have such a large proportion of children Why is the population of China still growing even though the Chinese government is enforcing a one child per couple population policy These are a small sample of the kinds of questions that can be addressed by Demography a simulation of population growth in an age structured population This program allows users to graphically enter age specific fertility and mortality rates for a population enter an age pyramid for an initial population and then observe the changes in population size and in the age distribution through time Demography allows students to ask a variety of what if questions to design and perform their own investigations to develop a deeper understanding of fundamental population concepts and to explore the implications of various population policies The direct manipulation graphical interface encourages exploration and makes the program accessible to introductory students Nevertheless the simulation model is capable of addressing problems that even graduate students in population biology will find interesting and challenging 68 Demography User s Manual Activity Issues in Human Population Growth 1 Making Some Predictions Based on your knowledge of the human population what do you think the current
49. hy program Read Appendix 1 Hardware and Software Requirements page 36 If you are familiar with the Macintosh but not with Demography Read the section entitled Using Demography page 6 If you have been through the features and want to know more details Read the section entitled Menus and Commands page 18 If you are an instructor and want to know how to use the program to prepare problem sets for students Read Appendix 3 Instructor Guidelines page 38 Also see Appendix 4 Sample Learning Module 1 page 44 Also see Appendix 5 Sample Learning Module 2 page 67 If you ve read through the manual but have found something that doesn t seem to work in Demography Read Appendix 2 IT DOESN T WORK page 37 Demography User s Manual 5 What You Need To Know Throughout this manual we will assume that you are already familiar with basic Macintosh operations and concepts If you are not comfortable with these refer to the Macintosh Owner s Guide or some other introduction to the Macintosh before starting To help you on your way the following is a list of Macintosh concepts you will need to understand along with a brief explanation For more information consult one of the references mentioned above or simply ask someone who has worked with a Macintosh before to explain briefly e Pointing Pointing simply refers to positioning the cursor which is shaped like a pointer over some object e Clicking Also known as s
50. imulation is running Go For To run a simulation for a specified number of time intervals choose the Go For command from the Control menu A hierarchical menu will appear giving you several choices for the number of time intervals to run the simulation If you wish to specify a number that doesn t appear in the menu choose Custom A dialog box will appear asking you to enter the number of intervals The simulation will run for the number of intervals you specify and then stop automatically The Go For command is inactive except when the simulation is stopped and will appear grayed out whenever the simulation is running Go To start the simulation running choose the Go command from the Control menu The simulation will continue running and the display windows will continue updating until you stop the simulation using the Stop command The Go command is inactive except when the simulation is stopped and will appear grayed out whenever the simulation is running Step To run the simulation for only one time interval choose the Step command from the Control menu The simulation will update all the display windows for only one time interval then the simulation will stop You can continue the run of the simulation from this point by choosing the Go command or you can continue to choose the Step command as many times as you want Each time it will update the simulation for one time interval The Step command is always
51. ingle clicking Position the cursor over the desired object and click the mouse button once For example Single click in a window to activate it means that if you position the cursor over a window and click once it will become the active window Clicking objects is typically used to select them see below e Double clicking Just like single clicking except that you click the mouse button twice in rapid succession instead of just once Dragging This is used to move objects around on the screen To drag an object grab the object by pointing to it and depressing the mouse button Don t click the button Depress it and hold it down Now move the mouse the object is dragged around on the screen When you have positioned the object where you want it release the mouse button to drop the object e Selecting This operation is used to pick one or more objects from a group of objects Selecting is usually accomplished by clicking on the object to be selected Typically selected objects will become highlighted to indicate they have been selected Example Select the mortality value for ages 20 25 by clicking on it The concepts listed above are few but are central to the operation of almost any Macintosh program There are a number of less fundamental concepts which we will ignore or will introduce as we encounter them 6 Demography User s Manual Using Demography This section provides basic information on how to use Demography
52. istics Survivorship vs Age and Stable Age Distribution Windows whenever you change the fertility mortality or current age distribution graphs Practice by changing the mortality graph and observing the changes that take place in the Statistics window The displays in two windows Population Size vs Time and Current Age Distribution change with time whenever you run a simulation Use the commands under the Control menu or the buttons on the Control Panel to see how the population size and age distribution change through time The Step command advances the simulation one time interval The Go command continues to advance the simulation until you choose Stop Choose the Step command several times and watch how the Current Age Distribution display changes For more precise control over how long a simulation is run use the Go For and Go Until commands available from the Control menu Now make sure the Population Size vs Time Window is open Choose the Go command and let the simulation run for a while If you watch the graph of population size as the simulation runs you will notice that it automatically rescales whenever necessary It may take you several runs to get used to the unexpected sudden changes in the shape of this graph that occur during rescaling Whenever you want the simulation to stop running choose the Stop command from the Control menu This only stops the simulation it doesn t quit the program or end the problem you are w
53. ize or density of a population Often results when individuals are competing for some limiting resource Dependency Ratio The fraction of a population that is dependent on the rest of the population In the human population this has generally been considered to be the fraction under 15 years plus the fraction over 65 years Doubling Time The time it would take a population to double given no changes in age specific mortality or fertility rates Any change in the fertility or the mortality graphs changes doubling time Demography represents doubling times as negative if the population is decreasing Negative values correspond to halving time Mean Life Expectancy How long an individual can be expected to live on average This is influenced only by the age specific mortality graph Sex Ratio The fraction of the population that is female Technically this value is not a ratio but this has become a common way of representing the gender distribution of a population The primary sex ratio is the proportion of births that are female Demography User s Manual 35 Stable Age Distribution The age distribution which the population will reach if allowed to progress until there is no longer a change in the distribution Survivorship The probability that an individual survives from age zero to a given age Total Fertility Rate TFR The total number of offspring a female would have on average if she were to live to the maximum age 3
54. lem file name The program will begin opening the windows of the problem file Demography User s Manual 7 Setting up a Simulation Displaying Population Characteristics The population characteristics that influence population growth are birth rates and death rates Birth rates or fertility rates and death rates mortality rates generally depend on age and sex Demography displays fertility and mortality graphically as functions of age e g Figure 1 These graphs can be changed at any time even when the simulation is running see Manipulating Population Characteristics Fertility vs Age F e r t i I i t y Figure 1 Fertility as a function of age The current position of the cursor is displayed in the box in the right hand side of the tool bar at the top of the window Other features are explained in the text In this instance fertility values are the average number of female offspring per female in a given age class In this example fertility values are displayed for five unit intervals If this represented a human population the units would be years and females between 35 and 40 would be expected to have 1 female offspring on average during the 5 year interval The values displayed in the Mortality vs Age Window report the probability that an individual in a given age interval will die before reaching the next interval This can be used to determine the population size of the next age in
55. m for Demography provides a quick alternative to the construction paper activity For more advanced students these activities may not be important The Demography exercises Parts 2 and 3 move from simple and highly structured to more complex and open ended We encourage this approach since it eases students into the program building both confidence and understanding If your students have had little experience using computers in your class even our simple initial exercise is likely to cause some frustrations In such circumstances we would recommend that you construct a few brief preliminary and highly directed exercises that will ensure that all students feel comfortable with the program and the material e g Change the mortality rate for the 20 25 age group to 0 5 and record any changes in life expectancy total fertility and doubling time Explain your observations As we help students through the structured exercises Part 2 see files in the Demography Exercises folder we try to avoid leading students to the right answer Rather we try to help them understand their observations clarify their thinking and design good experiments Initially some students may feel that this is a glorified game of hide and seek in a sense it is In addition though it is essential practice for their open ended investigation Part 3 and the interaction between faculty and student is much more rewarding than when guiding students through p
56. make the desired changes create a new mark and then delete the old one Demography and associated files are standard Macintosh files and can be copied in the usual ways when you are in the Finder for example by choosing the Finder s Duplicate command from the File menu or by dragging the file from one disk to another You will probably want to copy each of the files you have prepared onto a floppy disk that each student will use or copy the files onto each computer s hard drive 44 Demography User s Manual Appendix 4 Population Modeling Sample Learning Module 1 Introduction Models can be excellent predictive tools In fact every time we predict the outcome of a dynamic process e g tomorrow s weather an election global warming we build a model Our models may be simple or complex simplistic or thoughtful quantitative or qualitative realistic or naive In any case they are often used to make decisions take rainwear or not set environmental policies etc In the case of population models even simple quantitative models can be useful predictors of population dynamics Two simple kinds of models that describe how populations grow are exponential growth models and logistic growth models Exponential growth assumes that a population is growing at a constant rate per capita Logistic growth assumes that per capita birth rates and or death rates depend on population size As a consequence populations reach an equilibrium
57. nitial age structure Once the age structure has stopped changing stop your simulation and record your results in Figure 7 100 80 60 40 20 0 3 00 0 3 00 Trial a Trial b Trial c Initial Initial Initial Figure 6 Three different beginning age distributions all with the same mortality and fertility rates Demography User s Manual 59 Trial a Trial b Trial c End End End Figure 7 The ending distributions for the three trial populations shown in Figure 6 2 How can you explain these observations 3 What conclusions can you draw from these results Does the initial age distribution of a population influence its ultimate age distribution If you have time you could treat your answer to this question as an hypothesis and design further experiments to test it IMPORTANT Before you proceed to the next exercise make sure that you have talked to one of your instructors about your experiment and your results 60 Demography User s Manual Exercise 4 Stable Age Distributions Exercise 3 showed that when age specific fertility and mortality functions remain constant a population ultimately reaches a stable age distribution in which the proportion of individuals in each age class does not change with time even though the overall size of the population may be changing In this exercise we focus on the following question How is the shape of the stable age distribution related to a population s age specific f
58. o creatively explore and experiment Just as importantly it is designed to help you organize your explorations and keep track of your experiments You may stop a simulation at any time and mark your place so that you can return to it later to make comparisons to perform controlled experiments or simply to refresh your memory We hope that you find Demography to be an interesting and productive way to learn about the dynamics of populations In any case we would like to hear from you both students and faculty about your experiences with the program We are particularly interested in knowing the kinds of issues that you have explored how Demography helped and what kinds of limitations or problems you encountered Please write to the Biology Software Lab send us e mail BSL oregon uoregon edu or provide feedback through our World Wide Web site http Biology uoregon edu Biology WWW BSL BSL html 3 4 Demography User s Manual What You Should Read If you are Macintosh savvy and want to just dive right in Read Appendix 5 Exploring Demography Sample Learning Module 2 page 5 If you are unfamiliar with the Macintosh computer or computer terminology used in this manual Read the next section What You Need To Know page 5 If you are unfamiliar with a biological term that is used in this manual Read the section entitled Glossary page 34 If you want to know whether you have the right equipment to run the Demograp
59. of the current age distribution Display Settings The Summary Statistics Window displays the values of a number of composite variables calculated from fertility values mortality values and the population age distribution that summarize key characteristics of a population For example Doubling Time the number of time units that it would take for the population to double given current fertility and mortality values is often a useful indicator of how rapidly a population is growing Demography User s Manual 15 The Summary Statistics Window is updated immediately whenever the fertility mortality or current age distribution graphs are changed The meaning and or usefulness of each of these statistics will depend on the particular problem that you are investigating By choosing the Display command from the Settings menu you can select the appropriate set of statistics to display Running a Simulation m E i be Figure 9 The Control Panel buttons can be used to control the running of the simulation From left to right the buttons are Stop Go Step and Reset These commands are also available from the Control menu Once you have set up the simulation you can use the commands under the Control menu or the icons on the Control Panel Figure 9 to see how the population size and age distribution change through time To advance the simulation just one time interval choose the Step command from the Control menu o
60. onsumption curve shows the ideal amount of the resource that would be consumed by individuals in different age groups In Figure 6 for example consumption rates increase with age until about age 45 and then decrease Consequently everything else being equal a population consisting of mostly 20 50 year olds will put more pressure on this resource than populations consisting primarily of young or old individuals O consumption SB s o n s u m P t i o n Figure 6 The Consumption vs Age Window This window is only accessible when the density dependent model has been chosen from the Model Settings dialog box 2 Based on the ideal consumption curve and the current age distribution of the population the simulation calculates the total potential impact of the population on this resource during a time interval Potential impact is the total amount of resources that would be consumed if the availability of the resource were unlimited Demography User s Manual 13 3 Based on the total potential impact and the level of resources available the simulation estimates the actual impact of the population The relationship between these two is described by the graph in the Actual vs Potential Impact Window Figure 7 The actual impact will always be less than the potential impact If population sizes are small and the total impact is low then the actual impact will be close to the potential impact As potential impact increases
61. oose the appropriate settings and click OK to print your document 20 Demography User s Manual Quit To quit Demography choose the Quit command from the File menu If you have not saved the file a window will appear asking if you want to save the file All windows will disappear and the program will end Edit Menu Control Set Undo Cut 36H Copy 8C Paste aeu Clear Show Clipboard Undo To undo the most recent change to the model either a change in the shape of a graph or the running of a simulation choose the Undo command from the Edit menu You can only undo your last change see also Reset and Reset All under the Control menu Cut Use the Cut command from the Edit menu when you wish to cut selected text from the Notes Window associated with a mark see the Marks menu The selected text will be removed from the notes and placed on the clipboard for pasting somewhere else The Cut command is only active when the Notes Window is active and some text has been selected Copy Use the Copy command from the Edit menu to copy objects and place them on the clipboard for pasting into other documents Copy takes the visible object from the currently active window a graph a table or the selected text and places it on the clipboard Graphs are handled as picts and tables are handled as tab delimited text Demography User s Manual 21 Paste Use the Paste command from the Edit menu to take text
62. orking on You can stop and start the simulation as often as you like You are now familiar with the most essential features of Demography and ready to begin using the program to learn about the dynamics of populations Demography User s Manual 53 Exercise 1 Mortality and Life Expectancy The goal of this exercise is to examine how changes in age specific mortality rates influence mean life expectancy and to answer the following question Keeping all other things equal changing the age specific mortality of which age class will have the biggest impact on mean life expectancy To do this exercise using Demography open the problem file called Exercise 1 1 Before you start making changes to the mortality graph give the above question some thought make sure you understand the concept of mean life expectancy make an hypothesis and explain your reasoning 2 Design an experiment that could test your hypothesis Describe your design below Please keep in mind that for your experiment to be useful in evaluating your hypothesis you should try to change only one thing at a time If you want suggestions we ll be glad to help but you should feel free to describe your experiment and then go ahead and do it 54 Demography User s Manual 3 Describe your results Graph paper is available if you need it 4 What conclusions can you draw from this experiment Is it consistent with your initial hypothesis If not can you explain why
63. p them make connections between important scientific ideas and methods and crucial issues of public policy and personal well being To accomplish these objectives we have developed a teaching module that begins with very structured activities that address important concepts and moves toward open ended investigations that relate to public policy see Sample Teaching Module These activities provide a starting point for instructors interested in using Demography in their classes and labs Because of the flexibility of Demography and the open ended nature of these activities this module has been used with only slight modifications in high school classes and in ecology courses for biology majors Whether you choose to adopt this module or to adapt it to your setting we believe that you will find the progression from structured to open ended activities to be very effective Demography is still evolving New features and interface changes will occur over time A beta version of a cross platform JAVA implementation is also available on this CD We are quite anxious to hear your views of Demography and of the teaching module We would greatly appreciate any suggestions for improvement including ideas for new features For more information about Workshop Biology contact Daniel Udovic Director Workshop Biology Project Department of Biology 1210 University of Oregon Eugene OR 97403 1210 phone 541 346 5092 internet udovic oregon uoregon edu or s
64. please check the user s manual Demography User s Manual 61 2 Design an experiment or experiments that could test your hypothesis Describe your design below Please keep in mind that for your experiment to be useful in evaluating your hypothesis you should try to change only one thing at a time If you want suggestions we ll be glad to help but you should feel free to describe your experiment and then go ahead and do it 3 Describe your results Graph paper is available if you need it 62 Demography User s Manual 4 What conclusions can you draw from this experiment Is it consistent with your initial hypothesis If not can you explain why Can you suggest other experiments that could be done to help answer the original question 5 What are the some of the implications of your findings for the human population IMPORTANT Before you proceed to the next exercise make sure that you have talked to one of your instructors about your experiment and your results Demography User s Manual 63 Part 3 Independent Investigations and Presentations Now it is time for you to pose your own questions design and perform modeling experiments to test hypotheses that emerge from those questions and prepare a brief presentation to the class summarizing your work We have three suggestions for possible investigations listed below You may choose one of these if you wish but we also encourage you to consider other questions that you may hav
65. r example your experiments could examine the consequences of possible population policies for different regions of the world In the third class period each group will give a short presentation to the class 3 to 5 minutes summarizing their findings Your presentations should include a brief statement of the question s you were asking what your hypothesis was a description of the design of your experiment what you predicted the outcome would be what your results were and an interpretation of your findings Some Important Definitions e Age Specific Mortality Rate The fraction of individuals in a population that die during a given age interval For example if the probability of dying between age 5 and 10 is 0 25 or 25 that would be the mortality rate for that age class e Age Specific Fertility Rate The number of births per female during a specific age interval For example if on average each female has 1 5 children between the ages of 20 and 25 the fertility rate for that age class would be 1 5 Doubling Time The time it would take a population to double given no changes in age specific mortality or fertility rates Any change in the fertility or the mortality graphs will result in a change in Doubling Time Mean Life Expectancy How long an individual can be expected to live on average This is influenced only by the age specific mortality graph Total Fertility Rate TFR The total number of offspring that a female
66. r the Step icon from the Control Panel To have the simulation run until a specified time or for a specified number of time intervals choose the Go Until or Go For commands from the Control menu To have the simulation continue advancing until you tell it to stop choose the Go command from the Control menu or the Go icon from the Control Panel Whenever you want the simulation to stop running choose the Stop command from the Control menu or the Stop icon from the Control Panel This only stops the simulation it doesn t quit the program or end the problem you are working on so don t worry You can stop and start the simulation as often as you like If you wish to return to the initial state of a simulation with the fertility mortality and age distribution graphs as they were before you started the current simulation choose Reset from the Control menu or the Reset icon from the Control Panel A dialog box will appear asking whether you wish to mark the current spot before returning to the initial state see Menus and Commands Control Menu Reset for more details The Control Panel is a convenient way to run simulations Because of limited screen space however you may want to hide the Control Panel You may do so by clicking in the palette s close box or by choosing Hide Control Panel from the Control menu If the palette is hidden you may display it again by choosing Show Control Panel from the Control Menu 16 Demogr
67. rescribed steps that lead to the correct answer Students develop a deeper understanding of the concepts and gain important skills in designing and performing experiments and faculty gain important insights regarding student knowledge and misconceptions These exercises introduce students to the following concepts mean life expectancy and how it is calculated theimportance of infant mortality in determining mean life expectancy doubling time how delaying reproduction and reducing total fertility influence doubling time age pyramids stable age distributions how fertility and mortality values determine the shape of the stable age distribution 42 Demography User s Manual The open ended investigation Part 3 is the culmination of the module By this time students have been obtaining information about human population growth from a variety of resources and they have become comfortable with Demography They are now ready to use the program to build models that will help them evaluate for example possible consequences of adopting particular population policies in a particular country or region In the terminology of the BioQUEST project they are posing their own problems investigating possible solutions and in their classroom presentations persuading their peers In our general biology course this entire module takes four to five hours spread over three lab periods Students work in groups of two or three Th
68. results are easier to interpret z j Mortality vs fige M 0 r t a I i t y Figure 4 The Mortality vs Age Window for the sex differentiated model The sex differentiated model allows you to set different mortality and fertility functions for males and females Choose the sex that you wish to change by clicking on the appropriate letter in the legend In this example females are currently selected You may manipulate both curves simultaneously by selecting both sexes click on one letter first then hold the shift key down while clicking on the other letter In the simple model there is only one mortality curve and one fertility curve and the age distribution is always symmetric In the sex differentiated models there are two curves for fertility and mortality Figure 4 one for males square data points that are in blue if you are using a color monitor and one for females diamond data points that are in red if you are using color This is also indicated in the legend on each graph To make sure that you are editing the right curve first click on either the M or F in the legend and then use the mouse to move individual data points or to reshape the curve In the sex differentiated models the current age distribution may also be asymmetrical Modifying the values for one sex does not automatically affect the other Demography User s Manual 11 The three sex differentiated models differ in the way that fertility valu
69. rks of Adobe Systems Incorporated Microsoft Windows MS DOS and Windows NT are either registered trademarks or trademarks of Microsoft Corporation Helvetica Times and Palatino are registered trademarks of Linotype Hell The BioQUEST Library and BioQUEST Curriculum Consortium are trademarks of Beloit College Each BIioQUEST module is a trademark of its respective institutions authors All other company and product names are trademarks or registered trademarks of their respective owners Portions of some modules software were created using Extender GrafPak by Invention Software Corporation Some modules software use the BIioQUEST Toolkit licensed from Project BioQUEST Note An HTML version of this manual is available in the Documentation folder Table of Contents liic ez 1 ACKNOWLEDGMENTS 5 esssuudu cuavuRGEPIv DuxaFERENRRSER KE PEDNFEDDDR DIE EPI DRE EINE SEP ENE ES 2 AN OVERVIEW OF DEMOGRAPHY ceeeeseene enne nennen nennen nnne 3 WHAT YOU SHOULD HEAD onu neaduss s Pana cuia Duce Eau D MORE EUR MEExE MEE EEdMF P neri Ur OEKEE 4 WHAT YOU NEED TO KNOW rcscnspasuukeupasuP san CEEuE uus NE xRnEEE nd ER CK E UMEN EFE MEE cU ERE RUE 5 USING DEMOGHAPEPLHY uio eis festaccdexccadsessiaeencteauvemsebaeccsovenmnetiimererciacesancs 6 Running Demography osceicois seesseeisucsqerii e es s wu heed epi PLI CROSUITUNEEDE S OPURTUEUP SR PEIUS IUD M Re 6 Op nins a udis
70. roblem file already open If another file is open the Open command will be inactive will appear grayed out on the screen when you select the File menu Save the current file first if you want to then choose the Close command from the File menu Any parameter windows which are displayed will disappear Now choose the Open command under the File menu Notice that the Open command is now available The Save command under the File menu allows you to save a problem file along with any marks that you have set and any notes you have made for those marks It will remember the last time interval you reached and the position of all the parameter windows The Save As command under the File menu allows you to save a problem file under a different name from the one you opened For instance if you open a class problem file but you make changes to it and want to save it to a name you choose you would choose the Save As command from the File menu A window will appear asking you to name the file Enter in your new name and click on the Save button to save the file under your new name The old file will be the same as it was before and still have the old name Quitting To quit Demography choose the Quit command from the File menu or use the Command Q option to quit hold down the Command key which has the symbol on it and press the Q key on the keyboard If you have made any changes a dialog box will appear giving yo
71. s have such a large proportion of children Why is the population of China still growing even though the Chinese government is enforcing a one child per couple population policy These are a small sample of the kinds of questions that can be addressed by Demography a computer program that simulates exponential population growth By manipulating values for mortality rates fertility rates and initial population characteristics and then using the simulation to see how population characteristics change through time users of Demography can investigate important questions in population biology develop a deeper understanding of fundamental population concepts and explore issues related to population policy A key feature of Demography is the easy to use interface that allows you to rapidly and intuitively alter population characteristics even while a simulation is running and to instantaneously see the effects of your alterations For example changing the mortality rate of a particular age group such as 20 25 year olds can be done by simply manipulating a point on a graph using the mouse As soon as you release the mouse button Demography will recalculate important population statistics such as longevity mean life expectancy or doubling time If the simulation is running you will immediately see the effect of your changes on the growth of the population and on the shape of its age pyramid Demography is designed to make it easy for you t
72. sand in the population born during a time interval For example crude birth rates for the human population vary from nation to nation generally falling in the range from 10 per 1000 per year to 40 per 1000 per year Crude Death Rate The number of individuals per thousand in the population dying during a time interval For example crude death rates for the human population generally range from 5 per 1000 per year to 25 per 1000 per year Percent Juvenile The fraction of the current population that is below a certain age The default setting of 15 can be changed by choosing Model from the Settings menu Dependency Ratio The fraction of the current population that is dependent on the rest of the population In the human population this has generally been considered to be the fraction under 15 years plus the fraction over 65 years The default settings are 15 and 65 You can change this age by choosing Model Settings from the Settings menu Demography User s Manual 33 Percent Juvenile at the Stable Age Distribution The fraction of the population that would be below a certain age if the population was at its stable age distribution Dependency Ratio at the Stable Age Distribution The percent juvenile plus the fraction over a certain age if the population were at its stable age distribution Current Sex Ratio Sex differentiated model only The current sex ratio is the total number of females currently alive divide
73. several marks in the same file you can quickly move from mark to mark in a presentation using each mark to set up a simulation demonstrating a different point or using two or more marks to make comparisons When setting up problem sets for students it may be better to create a number of files with only one or two marks per file rather than a single file with numerous marks The problem is that in the current version of the program there is no mechanism for grouping related marks If students choose to set marks of their own the latter approach would lead to a single file with a collection of marks that are difficult to keep organized Demography User s Manual 43 Once you have created a file and set up all the marks that you need you may save the file using the Save or Save as commands under the File menu Demography will save all the initial values including model type and all the values displayed on the graphs for each mark that you set information about these marks such as the name and the notes that you entered for each mark and display information for each window such as the position and size of each window and whether it is open or closed If you discover that you want to edit a file marks can always be added or deleted In the current version of Demography individual marks cannot be edited If you wish to change the settings for a particular mark e g re position some of the windows you will need to go to that mark
74. sing the sex differentiated model click on the M or F in the legend before setting your data points in order to select which values you want to change male or female By selecting one and then shift clicking on the other you may select both sexes simultaneously Fertility vs Age BEE Fertility vs fige iem Displays the average offspring per time interval per individual as a function of age Also allows you to change these values by clicking on the points you wish to set by dragging the curve into the shape you want or by clicking on the buttons in the tool bar at the top of the window The button on the left shifts the graph to the left The center button shifts the graph to the right The button on the right allows you to multiply all values on the y axis by a constant amount The current position of the cursor is displayed in the box on the right hand side of the tool bar The scale on the y axis can be changed to allow for fertility values higher than 1 000 To increase the scale position the cursor near the top of the graph over the age group that you want to change The shape of the cursor will change from the cross hair to an arrow pointing straight up Clicking the mouse will cause the y axis to rescale To reduce the 28 Demography User s Manual scale simply reduce all the values of the fertility curve The y axis will automatically readjust The display can either be in a graphical form or in tabular
75. sk e On a color monitor the graphs will be displayed in color On a monochrome monitor the graphs will be displayed with different patterns Demography User s Manual 37 Appendix 2 It Doesn t Work Even the best program has some bugs in it However there are many situations in which there is some other problem something that is not an error at all I Can t Open the Program If Demography reports an insufficient memory error during startup the problem may be that there is not enough memory Are you sure the machine has at least 1 megabyte of free RAM memory Are you running other applications under MultiFinder which can be closed First find out how much memory you have Under the Apple menu select About Finder In System 7 this is called About This Macintosh You will see a dialog box detailing the current memory usage in your system The crucial figure is the largest unused block This value must be over 1000K in order for the system to run If it is not and there are no other applications currently running then Demography cannot be run on that machine If there are other applications currently running try quitting those applications in order to free up memory Can t Open a Saved Demography Document Was the document created with an early version 2 x of Demography Demography 4 1 will open documents created with version 3 0 but unfortunately it will not open documents created with version 2 0 or earlier
76. terval in the subsequent time interval For instance if the mortality rate of age interval 30 35 is 2576 and the number of individuals in the 30 35 age group at time 10 is 200 then the number of individuals in the age interval 35 40 at time 15 will be 150 The Current Age Distribution Window displays the percentage of the total population in each age interval in the form of an age pyramid For instance the lowest bar on the pyramid represents the percentage of individuals in the youngest age interval e g 0 5 the next higher bar represents 5 10 years old etc In each age class females are shown in red on a color monitor to the left of the center vertical axis males on the right in blue 8 Demography User s Manual Three other windows Summary Statistics Survivorship vs Age and Stable Age Distribution display data that are directly derived from the fertility and mortality graphs You cannot directly change these windows You can however investigate a number of important questions in population biology by studying how the values displayed in these windows are influenced by changes in the fertility mortality or current age distribution graphs Demography immediately updates the data in the Summary Statistics Survivorship vs Age and Stable Age Distribution Windows whenever you change the fertility mortality or current age distribution graphs For a more complete description of the meaning of the statistics or graphs that appe
77. tific notation for example 5 00 e 07 which represents 5 times 10 to the 7th power or 50 000 000 The display can either be in a graphical form or in tabular form To switch from one to the other click on the table or graph icon in the tool bar above the graph The values displayed are calculated from other population values you cannot change this window directly You may alter the current population size by choosing Variable Settings from the Settings menu and entering the value that you want into the appropriate field of the Variable Settings dialog box To see this window if it is not already shown choose the Population Size vs Time command from the Windows menu Demography User s Manual 31 Stable Age Distribution The age distribution of an exponentially growing population usually converges toward a stable age distribution with time This window displays the stable age distribution males are in blue on the left females are in red on the right The values displayed are calculated from the age specific mortality and fertility values you cannot change this window directly EI EI stable Age Distribution Male Female The display can either be in a graphical form or in tabular form To switch from one to the other click on the table or graph icon in the tool bar above the graph To see this window if it is not already shown choose the Stable Age Distribution command from the Windows m
78. tion for this period of time In this activity the simulation is set to run in 5 year increments Select Step from the Control menu a few times to see what happens Then select 100 from the hierarchical Go Until menu How does the shape of the age distribution graph compare to your prediction You can enter in the observed age distribution to the right of your prediction Can you explain any major discrepancies 4 Understanding Exponential Growth The initial population was 1000 Given the doubling time of the population based on the fertility and mortality values that you have entered predict how long should it take for the population to reach 32 000 Run the simulation and compare your prediction with the outcome of the simulation Predicted Time to 32 000 Observed Time Can you account for any discrepancies What happens to the age pyramid as time goes on Can you explain why 5 Data from the Population Reference Bureau To compare your estimates and results with the a model loosely based on 1995 PRB Data Sheets mark your place by choosing Set from the Marks menu and then go to the mark entitled PRB Data Demography User s Manual 71 Activity Il Stable Age Pyramids In activity I we discovered that after a number of time intervals the proportion of individuals in each age class reaches an equilibrium called a stable age distribution Demographers recognize that populations growing at different rates will hav
79. tion is running The Summary Statistics Window Figure 4 is one of three windows Statistics Survivorship vs Age and Stable Age Distribution that display data that are directly derived from the fertility and mortality graphs You cannot directly change these windows You can however investigate a number of important questions in population biology by studying how the values displayed in these windows are influenced by changes in the fertility mortality or current age distribution graphs Exercise 1 Summary Statistics Current Time 40 Doubling Time 23 2d Mean Life Expectancy 66 44 Total Fertility Rate 3 54 Figure 4 The Summary Statistics Window This window shows some basic statistics that Demography calculates from the fertility and mortality graphs You cannot directly alter the values in this window They will change automatically whenever you change the fertility or mortality graph You can control which statistics are displayed by selecting Display from the Settings menu Note that the Survivorship vs Age Stable Age Distribution and Population Size vs Time Windows were not displayed when the Intro Tour file was first opened As with all of Demography s windows they can be opened at any time by selecting them from the Windows menu Any window may be closed by clicking in its close box in the top left corner of the window 52 Demography User s Manual Demography immediately updates the data in the Stat
80. to immigration or emigration or both e Simple Model Sex Differentiated Model or Density Dependent Model The button next to the model that is currently being used by the program will be highlighted To change to another model click on the appropriate button For a description of the differences between models see Setting up a Simulation in the Using Demography section of this manual Display Choose the Display command from the Settings menu to select the statistics to be displayed in the Summary Statistics Window The choices are described below under Summary Statistics in the Windows Menu section Initial Setup Choose Initial Setup from the Settings menu to set the starting time of a simulation or to alter the current size of the population A dialog box will appear with boxes to enter the appropriate numbers The starting time can only be changed at the beginning of a simulation Fonts Demography User s Manual 25 Choose the Fonts command if you wish to change font sizes e g for presentations It is a good idea to size the window you re looking at to take up the whole screen if you increase font size Otherwise the graph may appear crowded and hard to read Marks Menu Marks Set Go To gt Remove gt Set To set a mark place the cursor over the Marks menu press the mouse button and drag down until the Set command is highlighted then release the mouse button A dialog box
81. treat it like any other mark Type a new name for this current state mark if you want Click on the OK button The program will go to the mark you requested 26 Demography User s Manual Remove If you decide you no longer need a mark that you have previously set you can remove the mark Move the cursor over the Marks menu press the mouse button and drag the cursor down until Remove is highlighted but don t release it yet Now drag the cursor to the right until you can see the names of the marks Drag down until the mark name you want is highlighted then release the mouse button A window will appear asking you to confirm that you want to remove the mark If not click on the Cancel button Otherwise click on the Remove button The mark you selected will be removed Notes After you have set a mark in a run of the simulation you can enter a note to keep track of some information about the mark Move the cursor over the Marks menu press the mouse button and drag the cursor down until Notes is highlighted but don t release it yet Now drag the cursor to the right until you can see the names of the marks Drag down until the name of the mark you want is highlighted then release the mouse button A text window will appear The window will contain any previously entered notes for this particular mark It will be empty if no notes were previously entered You may use the standard Macintosh methods for typing and editing text including
82. ts that could be done to help answer the original question IMPORTANT Before you proceed to the next exercise make sure that you have talked to one of your instructors about your experiment and your results Demography User s Manual 57 Exercise 3 Mortality Fertility and Age Distributions The goal of this exercise is to examine how changes in age specific mortality and fertility rates influence how a population s age distribution changes with time We will focus on the following question Assuming constant age specific death rates and birth rates how are changes in a population s age structure through time influenced by the population s initial age distribution This question may seem both abstract and obtuse but it has important consequences for a variety of population policies and is essential to understanding a particularly important concept in demography population momentum Momentum is the tendency for a rapidly growing population to keep on growing even after the implementation of policies designed to halt population growth This question is also important in understanding the demographic consequences of wars epidemics baby booms etc To study this question you can use Demography to set up populations with different initial age distributions and watch how the age distribution changes with time Open the problem file called Exercise 3 Notice that you have the following windows open and arranged in such a way that you
83. ty NZ Ed Louis The University of Nottingham UK Claudia Neuhauser University of Minnesota Angelo Collins Knowles Science Teaching Foundation Patti Soderberg Conserve School Terry L Derting Murray State University Roscoe Giles Boston University Louis Gross University of Tennessee Knoxville Yaffa Grossman Beloit College Raquel Holmes Boston University Stacey Kiser Lane Community College Daniel Udovic University of Oregon Rama Viswanathan Beloit College Linda Weinland Edison College Anton Weisstein Truman University Richard Wilson Emeritus Rockhurst College William Wimsatt University of Chicago Copyright 1993 2006 by Daniel Udovic Gordon Hennesy Will Goodwin Jasper Barber All rights reserved Copyright Trademark and License Acknowledgments Portions of the BIioQUEST Library are copyrighted by Annenberg CPB Apple Computer Inc Beloit College Claris Corporation Microsoft Corporation and the authors of individually titled modules All rights reserved System 6 System 7 System 8 Mac OS 8 Finder and SimpleText are trademarks of Apple Computer Incorporated HyperCard and HyperTalk MultiFinder QuickTime Apple Mac Macintosh Power Macintosh LaserWriter Image Writer and the Apple logo are registered trademarks of Apple Computer Incorporated Claris and HyperCard Player 2 1 are registered trademarks of Claris Corporation Extend is a trademark of Imagine That Incorporated Adobe Acrobat and PageMaker are tradema
84. u the opportunity to save your work before exiting the program 18 Demography User s Manual Menus and Commands This section will describe the menu structure of Demography and show you how to use the menus to choose commands to open files change parameters set marks run the simulation and print results File Menu pen New Use the New command if you don t have a file open and you want to start a new file from scratch Choose the New command from the File menu All seven Demography windows will appear with default parameter values You are now ready to start making changes to this new file Open To open a file choose the Open command from the File menu A window will appear asking you the name of the file you want to open and where on the disk this file is Click on the file name to select it then click on the Open button The Open command is inactive whenever there is already a file open and will appear grayed out Close the current file before opening a new one see Close command below Close Before you open a new file you must close the file that you currently are using by choosing the Close command from the File menu Demography User s Manual 19 If you have made changes to the current file and have not saved them a window will appear asking whether you want to save the changes To save the changes to this file click on the Yes button To close the current file without saving the changes click on
85. vals are far apart or you need to change fertility mortality and or age distribution settings along the way Exporting In preparing reports or handouts it is often useful to export data or graphs In Demography the contents of any window with the exception of the summary statistics window can be copied into the clipboard and pasted into other documents For example by choosing Copy when the Fertility vs Age Window is the active window either the graph or the table whichever is showing will be copied onto the clipboard The table could be pasted into a spreadsheet or into a word processing document or the picture of the graph could be pasted into word processing documents or into documents from drawing programs The contents of the notes windows associated with marks can also be copied and pasted into word processing documents Demography User s Manual 17 Printing You can print out a view of all the data in the windows as they are shown at any time during the run of a simulation Choose the Print Setup command from the File menu to make sure that the printing settings are okay for your printer Choose the Print command from the File menu to begin printing A dialog box will appear allowing you to choose which windows to print and how to arrange them Saving and Opening Problems The Open command under the File menu allows you to open a problem file that has been saved to disk You can do this only if there is not another p
86. vestigate and how to design your experiments than you will doing them Know when to seek help We will be around to guide you in developing questions and hypotheses and in designing your experiments We expect that some of you will feel lost at first If you fall into that category don t get frustrated get help 64 Demography User s Manual Document your assumptions A model is only as good as the assumptions on which it is based In this case you will probably be making assumptions about how a given policy change new disease or whatever will influence birth and death rates To persuade others of the validity of your models you will need to be able to defend your assumptions Writing up Your Work What question are you investigating Demography User s Manual 65 What is are your hypothesis es What experiment s can you do using the Demography program to test your hypotheses Make sure that you describe your predictions and your assumptions Also make sure you clearly explain how your experiment addresses your question 66 Demography User s Manual Describe your results Use tables or graphs if relevant What can you conclude from your results Does your evidence support or refute your hypothesis Does it lead you to propose other alternatives Describe the significance of your findings for human demography Demography User s Manual 67 Appendix 5 Exploring Demography Sample Learning Module 2 Introduction W
87. witching to 34 35 37 38 TFR See total fertility rate Tool bar 13 14 34 35 36 37 38 57 Total fertility rate 39 41 47 51 61 68 University of Oregon 1 3 4 7 44 47 Windows Current Age Distribution 36 Fertility vs Age 13 15 23 34 35 55 56 63 65 Mortality vs Age 13 17 34 35 55 63 65 Notes 48 Population Size vs Time 23 37 57 58 63 Stable Age Distribution 38 Summary Statistics 14 21 22 31 38 39 57 Survivorship vs Age 14 35 36 57 58 Windows menu 33 Workshop Biology 7 8 World Wide Web 7 9
88. xercises in Demography An Introduction to the Program The exercises below make use of a computer program called Demography In this section we introduce you to some of Demography s basic features You will learn more about the specific capabilities of the program as you progress through the exercises Please refer to the user s manual for details Demography allows you to construct graphs of birth rates fertility and death rates mortality as a function of age and to construct an age pyramid for a population From these graphs the program calculates critical demographic statistics for that population such as doubling time total fertility and mean life expectancy It also allows you to see how the size of the population and its age distribution change through time To begin find the problem file called Intro Tour on your hard drive or floppy disk in your computer and double click on it You should see four windows on your screen In addition to a statistics window entitled Intro Tour there should be two windows displaying line graphs Mortality vs Age and Fertility vs Age and one window displaying an age pyramid Current Age Distribution The values displayed in the Mortality vs Age Window Figure 1 report the probability that an individual in a given age interval will die before reaching the next interval This can be used to determine the population size of the next age interval in the subsequent time interval For instance i

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