This tutorial shows how you can conduct an independent t-test in SPSS. Note that, independent (sample) t-test is also called two sample t-test.
It deals with situations where X1 and X2 are from two different groups of people or objects.
For instance, in this tutorial, we are going to compare how female students differ from male students in writing scores. You can download the dataset here.
Steps of independent t-test in SPSS
Step 1: Select “Independent samples t-test”
Click Analyze, then Compare Means, then “Independent samples t-test”.
Step 2: Drag variables
Drag “write” as “Test Variable(s)” and “Gender_dummy” as “Grouping Variable(s)”. Further, for Gender_dummy, type 1 and 0 to indicate the group. Note that, 1 represents females and 0 represents males.
Step 3: Interpret the output of independent t-test in SPSS
Null Hypothesis: Men and women do not differ in writing scores.
Alternative Hypothesis: Men and women do differ in writing scores.
The following is the output of independent t-test in SPSS. As we can see, female students’ writing score mean is 54.99, whereas male students’ writing score is 50.12. The t-value is -3.734 and the degree of freedom is 198. Of importance, the p-value is smaller than 0.001. Thus, we reject the null hypothesis and conclude that male students and female students significantly differ in writing scores.
