SPSS for Unix - University of Windsor
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1. Replace exportfile with appropriate filename In some instances you may want to give the full pathname where the export file is to be stored Once the export file is in the designated operating system use the import command to read the import file The general syntax for reading an export file is IMPORT FILE exportfile Replace exportfile with the name of the file you moved from the source operating system If you want to create a system file from the export file add another command line to the above import command line SAVE OUTFILE systemfile Replace systemfile with an appropriate filename for storing the system file Reading compressed files For SPSS 6 1 on UNIX you can create and use compressed ASCII data files SPSS systems files and SPSS portable files This means you can compress any SPSS data files you have in order save disk space on your account To compress an SPSS file use the UNIX compress command which uses the Lempel Ziv compression method At your UNIX prompt type compress filename Replace the filename with the name of the file you want to compress This creates a new file with the extension Z For example if you compressed a file called test dat a compressed file called test dat Z would be created To read this file into SPSS use the FILE HANDLE command For example FILE HANDLE alias INPIPE zcat filename Z Replace alias with the file handle nickname you ll assign the compressed file2. commands can be up to 60 characters long You can insert as many of these commands as you wish into your program but don t place them between a procedure command and BEGIN DATA when the data are inline or within the data records Each command overrides the previous one However these two commands are optional TITLE Marketing Strategies SUBTITLE Frequency analysis DATA LIST command A typical SPSS program may start with a DATA LIST command followed by FILE definition if data are not inline variable names and column locations DATA LIST FILE pathname filename var1 col var2 col varn col The DATA LIST command tells SPSS to prepare to read some data The FILE definition portion of the data list points SPSS to the data file and indicates the format of the file The pathname shows the directory in which the data file resides Replace pathname with an appropriate directory name and filename with the name of the data file If the data file is in the default directory a pathname is not necessary In this document we assume the data file is stored in the same directory along with the command file If your data contains multiple lines per case observation indicate that along with the file definition DATA LIST FILE education dat FIXED RECORDS 2 1 id 1 2 gender 3 A test1 10 11 test2 25 26 2 final 1 4 2 iq 8 10 In the above command line the keyword FIXED indicates that the data are presented in fixed format
3. 000 Coefficient Cases 2 tailed Significance is printed if a coefficient cannot be computed CROSSTABS command The CROSSTABS procedure produces tables that are joint distributions of two or more variables that have a limited number of distinct values Again using the data described above if you wanted a breakdown of the students by gender and years of computer experience you would use the following command CROSSTABS sex by exp The following table presents the results SEX STUDENT GENDER by EXP YRS OF COMP EXPERIENCE EXP Page 1 of 1 Count UPTO 1 Y 2 YEARS 3 OR MOR R E Row 1 2 3 Total SEX F 7 7 8 22 FEMALE 55 0 Column 15 14 11 40 Total 37 5 35 0 27 5 100 0 Number of Missing Observations 2 DESCRIPTIVE command The DESCRIPTIVES procedure computes univariate summary statistics and standardized variables Using the sample data you could produce a table of basic statistics on four variables with the following command DESCRIPTIVES VARIABLES compopi mathati mathscor compscor The output for this command appears below Number of valid observations listwise 35 00 Valid Variable Mean Std Dev Minimum Maximum N Label COMPOPI 27 93 11 53 13 46 40 MATHATTI 38 83 12 55 15 50 40 MATHSCOR 40 65 7 57 20 50 37 COMPSCOR 35 95 6 57 24 48 38 FREQUENCIES command The FREQUENCIES procedure computes a table of frequency counts
4. FILE gt EXIT from any of the windows Note that an SPSS Motif session is very similar to an SPSS for Windows session For help on a specific topic during an SPSS Motif session click the menu bar Help option You may also click the Help pushbutton in an SPSS dialog box Another option is to press F1 at any time and select the topic you want Finally for specialized help click the Glossary pushbutton in an SPSS output window or the Syntax pushbutton in a syntax window For an overview of how to use the help system select On Help from the Help menu For more on an SPSS Motif session see SPSS Base System User s Guide for UNIX Printing files from Unix systems Ipr Pprintername filename Replace printername with the name of any of the UITS supported printers and filename with the name of the file you want to print You may download a file to your workstation and print it on your printer Contact a UITS consultant if you need help SPSS Data Sets SPSS system files A system file is a file that contains data and program together in binary format These files can be processed by computers much more quickly than can ASCII files Creating a system file substantially reduces the computer processing time especially with several data transformation steps System files are normally created with variable names value labels variable labels and data manipulation steps Suppose you want to create a system file from the data clas dat and command
5. all logged in users whoami who is logged on to this account pwd show current directory passwd change password cat file list the contents of the file cat file1 file2 gt file3 concatenates file1 and file2 into file more file list file page by page cp file1 file2 copy file1 to file2 mv file1 file2 rename file1 to file2 rm file delete the file head file show the beginning 10 lines of the file tail file show the last 10 lines of the files diff file1 file2 list the file differences wc file count the number of lines words and character in the file chmod mode file change the protection mode of the file finger username give information on the user specified chfn change finger information cd pathname change to directory pathname cd move one directory up cd move to the login directory mkdir pathname create a new directory pathname rmdir pathname remove directory pathname man command display UNIX manual entry for command logout end terminal session Refer to a UNIX commands document for further information Editors in UNIX You may use one of the several editors e g vi pico emacs available from UNIX Refer to a user s manual or at the UNIX prompt type man editor name for online manual For beginning UNIX users pico is the easiest to use Getting Started Organizing data for analysis A sample Suppose a researcher collected the following data during a study investigating computer anxiety in school children The informat
6. following lines into the profile file DISPLAY nnn nnnn nnnn nnnn 0 export DISPLAY C shell users should add the following line to the login file setenv DISPLAY nnn nnn nnnn nnn 0 Replace nnn nnn nnnn nnn with the IP number of your workstation To access SPSS from a windowing environment at the system prompt in X windows type spss If you want to use the same X window for other tasks type spss amp The first time you start an SPSS session the Startup Preferences dialog box opens To accept the default settings click OK This opens three other windows output window syntax window and data editor window At this point you can open an existing SPSS system file or define new data files through menus You can accomplish most of the tasks by simply pointing and clicking the mouse You can define the colors for your windows through bd border color bg background color and fg foreground color For example the command below will start a session with the specified colors for the windows spss bd red bg cyan fg black You can also define an alias in your kshrc or cshrc for running SPSS The default workspace during a Motif session is 1512K To read your command file clas1 sps into an SPSS Motif session select FILE gt Open gt SPSS Syntax To execute the job click the run button the second button from the right on the button bar The output will be stored in the output window To exit the session select
7. g arithmetic statistical logical that can be used with the compute command COMPUTE subscore SUM item1 TO item5 COMPUTE x y 5 68 COMPUTE pctwages wages income 100 COMPUTE allavg MEAN qn1 to qn25 COMPUTE m SQRT x1 SELECT IF command SPSS allows you to control the number and groups of cases used in analysis by selecting the observations you specify with the SELECT IF command These selections can be either temporary or permanent SELECT IF sex EQ M This command selects cases for which the variable sex has the value M The SELECT IF command permanently selects cases unless it s preceded by the temporary command TEMPORARY SELECT IF sex EQ M FREQUENCIES VARIABLES salary age In this case the temporary selection of male population ends as soon as the FREQUENCIES procedure is executed You may also use SELECT IF to set multiple conditions Suppose you want to permanently select for further analysis all the males over 40 years of age You may issue following the command SELECT IF sex EQ M AND AGE GE 40 There are a number of logical e g AND OR ANY and relational operators e g EQ NE GT LT GE you can use for data transformation COMMENT command Comments can help you and others review what you intend to accomplish with individual commands and blocks of commands SPSS ignores the comment part when it runs a job You can insert comments using the COMMENT command or an asterisk or by
8. item50 1 50 3 ascale1 TO ascale5 1 10 Note that on record 3 there are 5 variables with a total of 10 columns SPSS automatically divides the 10 columns equally among the 5 variables You can also use the keyword TO in a number of command lines e g VALUE LABELS RECODE FREQUENCIES RECODE and COMPUTE commands The ability to transform data is another important feature of SPSS Two commands that form the core of the transformation language are RECODE and COMPUTE The RECODE command is used to change the coding scheme of an existing variable on a value by value basis or for ranges of values To recode the values of item3 item9 and item21 from 5 4 2 and 1 to 1 2 4 and 5 use the command below RECODE item3 item9 item21 5 1 4 2 2 4 1 5 There are a number of keywords that could be used with the recode command RECODE age LO THRU 20 1 RECODE age LO THRU 20 1 ELSE 2 RECODE item1 TO item4 0 1 1 2 0 ELSE SYSMIS RECODE age MISSING 9 18 THRU Hl 1 0 THRU 18 0 INTO voter RECODE state MI MN The COMPUTE command is used to create a new variable or transform an existing one using information from other variables in your file The COMPUTE command generates a variable on your active file on a case by case basis To compute a variable specify the target variable on the left of the equals sign and the expression on the right COMPUTE subscore item1 item2 item3 item4 item5 There are several functions e
9. job runs in the background type spss m lt clas1 sps gt clas1 out amp You will see a process identification number PID for the background task and your terminal will be free for other computing To check the status of the job at the system prompt type the ps command Once the job is executed the listing file will be stored in the default directory or in the directory you specify 4 Sending jobs to a batch queue Batch queues are available on the SP You must submit CPU intensive jobs to the batch queue for execution Jobs that exceed the limits described below will be terminated automatically There is a special queuing system on Research SP e g aries05 for submitting long SPSS jobs to run in batch mode CPU intensive jobs requiring more than 20 minutes of CPU time must be submitted to IBM s LoadLeveler batch queuing system Two types of queues are available for statistical jobs on ariesO5 They are stat jobs requiring up to 8 day of CPU time To submit an SPSS job to LoadLeveler create a script file e g spsjob1 with the following lines requirements Feature spss group standard initialdir directory error filename class stat queue spss m lt inputfile gt outputtfile Replace directory with the directory where the command file is stored Replace filename with a name for the LoadLeveler error log file which will be stored in the same directory Replace inputtfile e g cla
10. the commands and paste them to the Input window You can get help by pressing Esc 1 and selecting manager help To exit a Manager session press Esc 0 and select exit Below is a brief summary of the keyboard mapping during a Manager session Command Key run menu Esc 0 information Esc 1 windows menu Esc 2 files menu Esc 3 lines menu Esc 4 look menu Esc 5 go to menu Esc 6 mark unmark menu Esc 7 marked area menu Esc 8 write delete file Esc 9 switch Input Output Esc S menu mode Esc 1M edit mode Esc E switch mode Esc S menu off Esc M top menu Esc Esc exit Esc 0 E Use the arrow keys to move the cursor in any window Not all keys become active as soon as you start a Manager session Some work only after you incorporate lines into the Input Window For example Esc 8 becomes active only after you press E sc 7 and mark lines See the SPSS Base System User s Guide for UNIX for information on the SPSS Manager session 3 Non interactive session To initiate a non interactive session you need a command file saved with all the necessary SPSS commands you want to use In this instance we created a command file clas1 sps with its data file clas dat To execute the command file clas1 sps non interactively at the system prompt type spss m lt clas1 sps gt clas1 out The output file will be stored as clas1 out You cannot use the terminal while the job is running However if you want to free the terminal for other work while the
11. 28 EXP NSEX 903 184 2 451 592 3 972 028 Explained 1319 489 5 263 898 2 321 064 Residual 3865 286 34 113 685 Total 5184 775 39 132 943 42 cases were processed 2 cases 4 8 pct were missing For further details on data definitions and procedures see the SPSS Reference Guide Release 6 1 and SPSS Advanced Statistics Release 6 1 Writing an SPSS syntax file Now that we have looked at the steps involved in creating an SPSS program the next step is to write one This example is for the sample research topic we discussed earlier Suppose you decided to include your data within inline the program file First look at the program file in its simple form TITLE COMPUTER ANXIETY IN MIDDLE SCHOOL CHILDREN DATA LIST ID 1 2 SEX 3 A EXP 4 SCHOOL 5 C1 TO C10 6 15 M1 TO M10 16 25 MATHSCOR 26 27 COMPSCOR 28 29 MISSING VALUES MATHSCOR COMPSCOR 99 BEGIN DATA data entered here END DATA LIST VARIABLES SEX EXP SCHOOL MATHSCOR COMPSCOR CASES 10 FREQUENCIES VARIABLES SEX EXP SCHOOL FINISH The program begins with an optional TITLE command The DATA LIST command names the variables followed by the column specification for each The TO keyword specifies the names of variables in sequential order Missing values for the two variables mathscor compscor are declared through the MISSING VALUE command A comment is added to the end of the missing value command demarcated by Since the data are inline the beginning of the data
12. Introduction How to use this document This document is intended to introduce SPSS for the UNIX environment The University of Windsor has SPSS on Unix available on the ARC1 server Features of SPSS Data management capabilities include Detailed labeling of variables and data values additional documentation of data sets storage of data and documentation in system files Flexible definition of missing data codes Permanent and temporary transformation of existing variables and computation of new variables conditional and looping structures for complex data transformations Reading raw data files in a wide variety of formats e g numeric alphanumeric binary dollar date and time formats Reading hierarchical and other non rectangular raw data files Reading combining outputting multiple files Reading matrices for input to procedures Flip command to switch the columns and rows in a data set Macro facility to build ones own block of SPSS syntax elements and to control the execution of these blocks Ability to read and write to compressed files Statistical procedures for data analysis include The EXAMINE procedure to explore data sets before deciding on the course of data analysis to perform Descriptive statistics frequency distributions and cross tabulations bar charts histograms and scatterplots The RANK procedure which produces ranks normal scores Savage scores and percentiles for numeric variab
13. It can be up to 8 characters long Replace filename Z with the name of your compressed file remember to always have a Z extension This can either be an ASCII data file or an SPSS systems file Be sure also to include the path of the data file if the file is stored somewhere other than the default directory from which you are running SPSS For example if you had an ASCII data file called test dat with 10 variables v1 v10 that you wished to compress and then access the command to compress the file is compress test dat To use this file in SPSS use the following SPSS commands FILE HANDLE test inpipe zcat test dat Z DATA LIST FILE test v1 to v10 You can then execute this command file as you normally would If you are using a compressed SPSS systems file you would use the same syntax but you would use the GET FILE command instead of a DATA LIST statement If test dat was an SPSS systems file instead of a compressed ASCII file you would replace the second line above with GET FILE test Finally if test dat were a compressed SPSS portable file you would use the IMPORT FILE command IMPORT FILE test Transferring files between SPSS and SAS SPSS can read SAS transport format files and create SPSS system files The general syntax for reading a SAS transport format file and creating an SPSS system file is GET SAS DATAz sastransportfile SAVE OUTFILE fromsas sys Replace sastransportfile with the name
14. That is each variable is recorded in the same location on the same record for each case FREE and LIST are other two format types In FIXED format a fortran like format specification is also permitted DATA LIST FILE clas dat FIXED RECORDS 2 1 id gender testi test2 F2 0 A 6X F2 0 13X F2 0 2 final iq F4 2 3X F3 0 The RECORDS subcommand specifies the number of records lines per observation This subcommand is not used with free or list formats In the above example the variable id is in columns 1 2 on the first record of each observation The variable sex is alphanumeric character as indicated by A and is in column 3 of the first record The DATA LIST command by default assumes all the variables are numeric If a variable is alohanumeric you need to define it If an alphanumeric variable has 2 characters specify it as A2 3 characters as A3 and so on The variable final is in columns 1 4 and the variable iq is in columns 8 10 both on the second record By default DATA LIST assumes that the data are whole numbers or that decimal points have been recorded on the data file To indicate non integer values when a decimal point is not actually coded in the data specify the number of implied decimal places in parentheses following the column specification In the above example the variable final is in columns 1 4 but the last 2 digits are decimal points Since this decimal point was not included when the data were entered you indic
15. YEARS 3 3 OR MORE YRS SCHOOL 1 RURAL 2 CITY 3 SUBURBAN C1 TO C10 1 STRONGLY DISAGREE 2 DISAGREE 3 UNDECIDED 4 AGREE 5 STRONGLY AGREE M1 TO M10 1 STRONGLY DISAGREE 2 DISAGREE 3 UNDECIDED 4 AGREE 5 STRONGLY AGREE PRINT FORMATS COMPOPI MATHATTI F2 0 Specifying the print format LIST VARIABLES SEX EXP SCHOOL MATHSCOR COMPSCOR COMPOPI MATHATTI FORMAT NUMBERED CASES 10 only the 1st 10 cases FREQUENCIES VARIABLES SEX EXP SCHOOL STATISTICS ALL TEMPORARY SELECT IF SEX EQ F FREQUENCIES VARIABLES SEX EXP SCHOOL STATISTICS ALL CROSSTABS TABLES SEX BY EXP SCHOOL DESCRIPTIVES COMPOPI MATHATTI MATHSCOR COMPSCOR ANOVA COMPOPI BY EXP 1 3 NSEX 1 2 FINISH Some of the commands in this program may need further discussion The RECODE command reverses the values of a number of variables It also changed the variable sex to a numeric variable named nsex SPSS does not permit you to change a variable from string to numeric or from numeric to string by recoding it into itself You can use the INTO keyword to specify a new variable in recode command String variables cannot be used on a number of mathematical operations and functions The new variable nsex is later used in the ANOVA procedure Two new variables compopi and mathatti are created using the COMPUTE command Two methods arithmetic operator and statistical function SUM are used to create new variables for the purpose of illustrat
16. and percentages for the values of individual variables This command is typically used to get the breakdown of categorical variables Below is an example of the syntax for obtaining a distribution of the variable SCHOOL which indicates the type of school the students in the sample data set come from FREQUENCIES VARIABLES school The following output is generated SCHOOL SCHOOL REPRESENTING Valid Cum Value Label Value Frequency Percent Percent Percent RURAL 1 13 31 0 32 5 32 5 CITY 2 13 31 0 32 5 65 0 SUBURBAN 3 14 33 3 35 0 100 0 2 4 8 Missing Total 42 100 0 100 0 ANOVA command The ANOVA procedure performs analysis of variance for factorial designs The example below attempts to test the relationship between gender and computer experience again drawing from the sample files Notice that the SEX variable has been recoded into a new variable called NSEX because the original variable was a character variable which cannot be used in many of the more sophistical statistical procedures ANOVA COMPOPI BY EXP 1 3 NSEX 1 2 A summary of the results is as follows ANALYSIS OF VARIANCE COMPOPI TOTAL FOR COMP SURVEY by EXP YRS OF COMP EXPERIENCE NSEX UNIQUE sums of squares All effects entered simultaneously Sum of Mean Sig Source of Variation Squares DF Square F of F Main Effects 742 012 3 247 337 2 176 109 EXP 566 882 2 283 441 2 493 098 NSEX 340 840 1 340 840 2 998 092 2 Way Interactions 903 184 2 451 592 3 972 0
17. ate this in the format statement MISSING VALUE command There are several options to indicate missing values in a data file You can leave missing values blank or code them with a specification of your choice When you leave a field blank SPSS by default assigns a system missing value to that field If you decide to leave a blank for missing values a MISSING VALUE command is not required in the program file However some researchers choose to assign unique values for missing data e g 9 99 0 MISSING VALUES salary 99 age 9 In the above example missing values for salary and age are coded as 99 and 9 respectively VARIABLE LABLES command The VARIABLE LABELS command in SPSS is used to assign an extended descriptive label to variables Specify the variable name followed by a blank and the associated label enclosed in apostrophes or quotation marks Each variable label can be up to 120 characters long but most procedures print fewer than 120 characters for each label in the output VARIABLE LABELS salary current salary for the employee exp years of experience with the present employer age present age VALUE LABELS command The VALUE LABELS command is used to assign labels to the values of variables The value labels command is followed by a variable name or variable list and a list of values with the associated labels Value labels can have a maximum of 60 characters however most procedures print out fewer characters f
18. clas1 sps files created earlier Add the SAVE OUTFILE immediately after the VALUE LABELS command in the command file The general syntax for creating a system file is SAVE OUTFILE systemfile Replace systemfile with an appropriate path name and filename for storing the system file Note Any external file in SPSS that is encased in single quotes must be in the correct case A system file is readable only by the operating system from where it was created The general syntax for accessing a system file is GET FILE systemifile Replace systemfile with the name of the file Specify a full pathname when applicable SPSS portable files If you are using SPSS under other operating systems e g Macintosh Windows you can move your SPSS files to a Unix environment However SPSS system files created under one operating system are not readable under another system For example an SPSS system file created under Windows is not readable under Unix There are variations of Unix and system files created under one Unix platform are not readable from anoth er For example a SPSS system file created under SunOS Steel is not readable under IBM AIX SP and vice versa When you want to use a system file created under one operating system on another you must create an export file and move it to the host machine The general syntax irrespective of the operating system for creating an export format file is EXPORT OUTFILE exportfile
19. displayed on the screen If you specified an output filename the output would be stored in that file Note if you have a FINISH command in the file you are rea ding in from a prompted session it will terminate your session 2 SPSS Manager session SPSS Manager is a character based interactive interface designed to help you build and run SPSS commands To invoke SPSS under a Manager session at the system prompt type spss m This opens two windows in the SPSS Manager the Input window at the bottom of your screen and the Output window at the top Type your command lines in the Input window To run the job first move the cursor to the beginning of the line where the execu tion should begin then open the run menu by pressing Esc 0 and selecting run from the cursor You can also read in a file you already created and saved into a Manager session press Esc 3 and select Insert file For example to read in the command file clas sps at the Manager session press Esc 3 then select Insert f ile At the File to Insert prompt type clas1 sps Now the file will be included in the window Move the cursor to the beginning of the file and press Esc 0 and select run from cursor The output will appear in the top por tion of the screen To move into the Output window or Input window use Esc 2 and switch You can also run a Manager session in Menu Mode press Esc 1 and select M The Menu mode has an interface similar to SPSS PC where you can select
20. e 2 agree 3 undecided 4 disagree 5 s disag V2 1 7 i V3 1 8 V4 1 9 j V5 1 10 V6 1 11 V7 1 12 m V8 1 13 v9 1 14 i V10 1 15 3 S1 1 16 S2 1 17 3 1 18 S4 1 19 5 1 20 9 S6 1 21 S7 1 22 S8 1 23 S9 1 24 i S10 1 25 7 MATH 2 26 27 COMP 2 28 29 In this code book VARIABLE NAME stands for the name of the variable in the data and WIDTH stands for the number of fields taken by each variable For example the variable ID takes a maximum of two fields columns since the highest ID number is 40 Similarly EXP takes a maximum of one column field COLUMNS stands for the column number s on a given line where SPSS can find a value for each variable VALUE LABELS means the value represented within a variable For example within the variable SEX M represents male and F represents female students Within the variable SCHOOL 1 2 3 represent rural city and suburban schools respectively Now examine how the data layout will look on a coding sheet or on a computer terminal These variable values are being copied from questionnaires filled in by students The variables are placed into appropriate columns based on the code book prepared earlier 01M121231 122452221 13541213944 02F2232544521 1233445422212526 03F11211551141121122155114845 Note that on every line a given variable appears in the same column s For example the variable GENDER always appears in column three In the above data no blank space is
21. enclosing the comment within and in any command line COMMENT select all the males from the data Comment can also be inserted with an asterisk as in select all the cases with values 1 or 2 for the variable income You may also use the comment within and three categories are to be created Another reasonable place for the comment is at the end of the line in which case the closing is optional as in RECODE income 2 3 1 else 1 recoding the values for income 2 Data analysis SPSS has a variety of procedures for statistical analysis you can choose based on your needs e g FREQUENCIES DESCRIPTIVES CROSSTABS CORRELATIONS ANOVA MANOVA and REGRESSION Below are some brief examples with samples of the output these commands generate Note the data used in this section are described above The actual program file is in the next section titled Writing an SPSS program CORRELATION command The procedure CORRELATIONS produces Pearson product moment correlations with significance levels and optionally univariate statistics covariance and cross product deviations For example to correlate a single variable against three other variables you would use the following syntax CORRELATIONS VARIABLES compopi WITH mathatti mathscor compscor The following correlation matrix is produced Correlation Coefficients MATHATTI MATHSCOR COMPSCOR COMPOPI 2589 1743 7719 40 37 38 P 107 P 302 P
22. ion The PRINT FORMATS command changes the print formats for the variables specified on the command When you create a new variable e g compopi mathatti using the transformation language the default format is F8 2 To override this feature and to get the value printed as you want use the PRINT FORMAT command The TEMPORARY command is used to create a temporary data set with the female population alone and to runa frequency analysis with selected variables Once the frequency procedure is executed the temporary transformation ends The ANOVA procedure runs a two way ANOVA with compopi as the dependent variable and exp and nsex as the independent variables A number of options e g MISSING REG STATISTICS are available with this and other procedures used in the program Executing an SPSS program Suppose that you saved the above program in a file clas1 sps in your root directory to obtain a copy see Sample Files above There are several ways to execute these commands 1 Prompted session You may access SPSS in a prompted session interactive line mode You don t need an X terminal to start a prompted session To begin a prompted session at the system prompt type spss m In the above command m is one of several switches available with SPSS under Unix Them switch suppresses the Manager mode or the Window mode A few of the other switches available in SPSS under Unix are e t output to send the listing file to the te
23. ion collected on each student is identification number gender school system previous computer experience scores on a 10 item Likert type computer anxiety scale scores on a 10 item Likert type mathematics anxiety scale math score for a given testing period and computer test score for the same testing period The researcher wants to write an SPSS program to analyze the data Now we ll look into creating an SPSS program for analyzing these data The first task is to present the data in an orderly form for the SPSS software to read it and analyze There are several variables involved in this research In SPSS variables are named with 8 or fewer characters but must begin with a letter Name these variables according to SPSS conventions ID student identification number GENDER gender of the student LEVEL level of previous computer experience in months yrs AREA location of school system V1 thru V10 10 scores on the computer anxiety scale S1 thru S10 10 scores on the math anxiety scale COMP computer test score for a given testing period MATH math score for the same testing period Next prepare a code book with details of the data layout Following is a code book for your research Preparing a code book would be helpful for researchers of all levels VARIABLE NAME WIDTH COLUMNS VALUE LABELS ID 2 1 2 GENDER 1 3 M male F female LEVEL 1 4 1 1 yr or less 2 2 yrs 3 3 yrs AREA 1 5 1 rural 2 city 3 suburban V1 1 6 1 s agre
24. left between variables You may choose to leave a blank space after each variable as 01M1212311224522211354121 3944 02F2232544521123344542221 2526 03F11211551141121122155114845 As long as you convey the format correctly to SPSS the format you choose should not have any impact on the analysis In the above layout there are only three lines of data and each line stands for an observation information about each person Note that each subject has only one line record of data Using an editor such as vi or pico you can enter the data directly into your account on a UNIX based system Or you can type the data using a microcomputer text editor and save it on a floppy diskette for transfer to a UNIX platform using FTP File Transfer Protocol or any other appropriate communication package Basic elements of an SPSS syntax file The SPSS program consists of commands for defining and analyzing your data In an SPSS program file there are two distinct parts 1 data definition and 2 procedure section 1 Defining data In the data definition section the variables involved in the study are specified followed by the locations columns in which they re entered This includes the number of columns occupied by each variable decimal points if appropriate and the type of variable numeric or string The data definition section may also contain information on specification of missing values for the data set variable labels and value labels for
25. les T tests univariate and multivariate analysis of variance and covariance including repeated measures and nested designs Multiple regression NonLinear Regression Constrained NonLinear Regression Loglinear models for discrete data probit models Factor and principle components analysis discriminant analysis cluster analysis multidimensional scaling Nonparametric tests Besides these capabilities SPSS add on modules feature Tables to produce simple or complex tabulation formatted for presentation Trends including time series plots plots of autocorrelation partial autocorrelation cross correlation function smoothing seasonal regression Box Jenkins methods spectral methods and forecasting Categories for doing conjoint analysis and optimal scaling UNIX basics In UNIX you may encounter the C shell csh Bourne shell sh and Korn shell ksh These are interpreters of command language telling the system to act on submitted commands Each shell has some unique features For SPSS it does not matter which shell you use You can access SPSS the same way regardlesss Helpful UNIX commands Below is a list of useful UNIX commands Bold type denotes a parameter that you must specify e g filename directory name etc Is list files in directory Is I list files in directory in detail quota display disk quota if any history see a list of commands executed so far date print date and time who see a list of
26. line is declared using the BEGIN DATA command and the end of the data line with the END DATA command The LIST procedure displays in standard format the values of the variables for 10 cases in the active file Using this procedure may be a good way to check whether the data are being read by program as you wanted them to read The CASE subcommand controls the number of observations to be processed for this procedure The FREQUENCIES command requests tables for 5 variables Next expand the program to include some additional features of SPSS The data file clas dat is an external file Comments are provided in several places for clarity TITLE COMPUTER ANXIETY IN MIDDLE SCHOOL CHILDREN DATA LIST FILE clas dat ID 1 2 SEX 3 A EXP 4 SCHOOL 5 C1 TO C10 6 15 M1 TO M10 16 25 MATHSCOR 26 27 COMPSCOR 28 29 MISSING VALUES MATHSCOR COMPSCOR 99 RECODE C3 C5 C6 C10 M3 M7 M8 M9 1 5 2 4 3 3 4 2 5 1 RECODE SEX M 1 F 2 INTO NSEX char var into numeric var COMPUTE MATHATTI M1 M2 M3 M4 M5 M6 M7 M8 M9 M10 COMPUTE COMPOFPI SUM C1 TO C10 total 10 items using SUM function VARIABLE LABELS ID STUDENT IDENTIFICATION SEX STUDENT GENDER EXP YRS OF COMP EXPERIENCE SCHOOL SCHOOL REPRESENTING MATHSCOR SCORE IN MATHEMATICS COMPSCOR SCORE IN COMPUTER SCIENCE COMPOPI TOTAL FOR COMP SURVEY MATHATTI TOTAL FOR MATHATTI SCALE VALUE LABELS SEX M MALE F FEMALE EXP 1 UPTO 1 YEAR 2 2
27. of the SAS transport format file and fromsas sys with an appropriate filename to store the system file An SPSS system file or export file is also readable during a SAS session SPSS can also read data files created using Lotus Excel dBase and so on Refer to the GET TRANSLATE command in the SPSS System Syntax Reference Guide Release 5 0 or 6 1
28. or each label VALUE LABELS age 1 20 29 yrs 2 30 35 yrs 3 36 41 yrs 4 42 yrs sex M male F female Reading inline data Earlier in this section you used the FILE command to indicate the name of the file where the data is stored If your data are inline omit the FILE subcommand on the DATA LIST command You ll need two SPSS commands to separate lines containing data from lines containing SPSS commands BEGIN DATA and END DATA TITLE employee grievances study DATA LIST id 1 2 sex 3 A salary 5 11 2 position 15 age 18 19 VARIABLE LABELS id identification number salary current salary position job classification age present age VALUE LABELS sex M male F female position 1 managerial 2 professional 3 clerical MISSING VALUES salary 999 position 0 BEGIN DATA 01M 1838235 1 23 02F 2145325 1 31 03M 2382329 2 29 04F 126825 3 27 END DATA SPSS allows you to create and refer to a set of variable names by using the keyword TO Suppose you have 20 items for a questionnaire in your study When you are assigning names item1 TO item25 is equivalent to 25 names item1 item2 item item24 item25 The prefix can be any valid name and the numbers can be any integers as long as the first number is smaller than the second and the full variable name including the number does not exceed 8 characters DATA LIST FILE dstudy dat RECORDS 3 1 id 1 3 qn1 TO qn25 4 28 2 item1 TO
29. rminal and to a file simultaneously Replace output with an appropriate name e p displays output on the terminal one screen at a time This is the same as the more command in Unix e s workspace replace workspace with the number of bytes to be used for working storage Specify a number followed by k or m megabytes The default is 512K This is sufficient for most jobs Suppose you want to start a prompted SPSS session with the output file stored as test lst and want to view the output on a terminal page by page You would type spss m p s 300k t test Ist Command switches are applicable for any mode of SPSS access You must specify them when you invoke SPSS See the SPSS Base System Users s Guide for UNIX for further information on switches available with SPSS Once SPSS is invoked you will see the SPSS prompt SPSS gt at the input line This means that SPSS is ready to accept your input commands Each SPSS command is terminated by a period A command starting with a keyword may span across several lines A command terminator informs SPSS that a command is complete Below is a sample SPSS prompted session Start your prompted session by typing spss m at the system prompt When you see SPSS gt type the following lines pressing ENTER after each line SPSS gt data list free id age educ exper salary SPSS gt begin data DATA gt 01 32 16 4 32000 DATA gt 02 24 13 2 19000 DATA gt 03 42 18 8 41000 DATA gt end da
30. s1 sps with the name of the SPSS command file and outpuifile e g clas1 out with an appropriate name for storing the output from the run To submit the job at the system prompt type Ilsubmit spsjob1 The output files will be stored in the directory you specified in the script file You may log out after submitting the job For more information on batch jobs on SP System visit e The UITS Research SP System Submitting Batch Jobs to LoadLeveler Accessing SPSS from an X terminal If you want to use all the features of SPSS for Unix Release 5 0 or higher you must access it from a Unix X windows environment One of the most attractive features of the latest versions of SPSS is the Motif graphical users interface GUI which makes it easier to learn and use This provides descriptive menus and simple dialog boxes providing a point and click environment for SPSS that is very similar to the Windows and Macintosh versions The Motif interface also provides several other features e Data Editor A versatile spreadsheet like system for defining entering editing and displaying data e High resolution graphics High resolution full color charts and graphics as a standard feature in SPSS Base system e Chart Editor A highly visual object oriented facility for manipulating and customizing the many charts and graphs produced by SPSS Before invoking SPSS set up the terminal for proper display Korn or Bourne shell users should add the
31. ta Preceding task required 02 seconds CPU time 105 32 seconds elapsed SPSS gt list var all ID AGE EDUC EXPER SALARY 1 00 32 00 16 00 4 00 32000 00 2 00 24 00 13 00 2 00 19000 00 3 00 42 00 18 00 8 00 41000 00 Number of cases read 3 Number of cases listed 3 Preceding task required 01 seconds CPU time 12 seconds elapsed SPSSsz finish End of job 8 command lines 0 errors 0 warnings 0 CPU seconds In the above session you typed in the data lines You may also use the data list file myfile dat command to read an external data file into a prompted session During a prompted session you have the option of using the INCLUDE command t o read in a stored command file If you decide to type in the command lines you can save the commands you type in a journal file for later use To turn the journaling on at the SPSS gt prompt type set journal You can stop journaling by typing s et journal off and resume it by typing set journal on For help at the SPSS gt prompt type help You may also type help to receive a description of the help facilities or help keyword where you replace keyword with by anova manova t test report etc to get help on the topic yo u want To end a prompted session at the SPSS gt prompt type finish If you decide to read in a command file e g clas1 sps at the SPSS gt prompt type include clas1 sps The file will be read into the SPSS session and the commands executed The listing will be
32. the variables involved Finally a data definition section can contain a number of data transformation manipulation commands to organize the data before analysis All SPSS commands must begin in column one and continue on for as many lines as needed Command lines that continue on more than one line must be indented at least one column for continuation lines Each command should end with a period which serves as the line termination character although it is not required when running SPSS in batch or non interactive modes A period at the end of each command is always required in DOS Windows and Macintosh versions of SPSS so it is a good practice to always use a command terminator regardless of operating system The SPSS commands are not case sensitive but it preserves upper and lower case within labels and strings SPSS also distinguishes between an uppercase and lowercase character within a string variable For example in a variable gender the value F is not the same as the value f Unix is case sensitive however education dat and EDUCATION DAT are different filenames in Unix Each command begins with a keyword followed by command specifications Keyword and specifications are separated by at least one space TITLE command The first line of an SPSS program may be a TITLE command This command gives a title for your study and prints it at the top of every page of output The SUBTITLE command gives subtitles for your analysis Both of these
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