SPSS at Ole Miss: Part I

This is the first of a two-part article on SPSS at Ole Miss. In part one after introducing SPSS and looking at how to activate SPSS on willow and on PC, we look at an example program of SPSS that performs a t-test. Then, we see how “SPSS save files” are created by SPSS System. In the following article we show how the “SPSS save file” created in this part is activated and the data and information is retrieved from it.

SPSS/PC is completely interactive and users only need to enter their data and then choose a particular routine to perform a specific procedure from many that are available to them. To activate SPSS on a PC click on the SPSS icon. After that, everything is menu driven and SPSS help may be utilized to get help.

To activate SPSS on willow, enter: spss -m part1.spss >my.out

In this example part1.spss is the user input to the SPSS software. If there are no errors, the output (result) from this run will be saved in my.out as requested by the user. Below is a simple example of SPSS program copied from willow. Please note that lines containing /**/ are comments and are not executed. These lines explain the SPSS instructions for performing the t-test. This file is also located at /users/local/appl/examples/spss/part1.spss on willow.

set width 80
run name t-test:example from pages 74 of Steel & Torrie
data list /ind 1 dep 4-7


/* */
/* There are two variables, ind located on col 1 and dep located on col. 4-7 */
/* */


t-test groups=ind/variables=dep


/* */
/* t-test is performed on var. dep. */
/* */


statistics all /* Generate all the statistics available to t-test.*/


/* begin reading data */
begin data
1 57.8
1 56.2
1 61.9
1 54.4
1 53.6
1 56.4
1 53.2
2 64.2
2 58.7
2 63.1
2 62.5
2 59.8
2 59.2
end data /* This line signals the end of the input data */


/* The following 2 lines create two special SPSS files that */
/* may be used by another program to perform more analysis */


export outfile=myportfile
save outfile='tdisk.sav'.


The last two lines of the above program create a binary data set called “tdisk.sav”. We will talk about how to activate this SPSS save file and retrieve data from it in the next article. Following result is generated when the above SPSS program is executed:

Variable of Cases Mean SD SE of Mean
-----------------------------------------------------------------------
DEP

IND 1 7 56.2143 3.002 1.135
IND 2 6 61.2500 2.302 .940
-----------------------------------------------------------------------

Mean Difference = -5.0357

Levene's Test for Equality of Variances: F= .019 P= .893

t-test for Equality of Means 95%

Variances t-value df 2-Tail Sig SE of Diff CI for Diff
-----------------------------------------------------------------------
Equal -3.34 11 .007 1.506 (-8.350, -1.721)
Unequal -3.42 10.90 .006 1.473 (-8.282, -1.789)
-----------------------------------------------------------------------

Continue to SPSS at Ole Miss: Part II.