T-test assess whether the means of two groups are statistically different from each other.

1. To perform a t-test, click on Analyze. Then click on Compare Means. For this demonstration we will perform a independent samples t-test, therefore click on Independent-Samples T Test.

2. The Independent-Samples T Test dialogue box will appear.

3. For this demonstration, we want to test if the mean age between those who are married and those who are not are statistically different. Therefore, age is the test variable and marital status is the grouping variable. Add Age in years to the Test Variable(s): text box by clicking the button with the right arrow.

4. Add Marital status to the Grouping Variable: text box by using the button with the right arrow next to the grouping variable text box.

5. SPSS does not know automatically what two groups you want to compare means. To tell SPSS which groups we want, we click on Define Groups button under the Grouping Variable: text box.

6. For this dataset, 0 indicated that a participant was unmarried and 1 indicated that they were married. Enter 0 for Group 1: and 1 for Group 2:

7. Click Continue.

Optional: You can select additional options or bootstrap by clicking the corresponding buttons on the right.