t Tests

IBM SPSS Step-by-Step Guide: t Tests

Note: This guide is an example of creating t test output in SPSS with the grades.sav file. The variables shown in this guide do not correspond with the actual variables assigned in Unit 8 Assignment 1. Carefully follow the Unit 8 Assignment 1 instructions for a list of assigned variables. Screen shots were created with SPSS 21.0.

u08a1: t Tests

Refer to the Unit 8 assignment instructions for a list of assigned variables. The example variables “lowup” and “final” are shown below.

Step 1. Open grades.sav in SPSS.

DAA Section 2: Assumptions of t Tests

To complete Section 2 of the DAA, you will generate SPSS output for a histogram, descriptive statistics, and the Shapiro Wilk test. (Levene Test output will appear in Section 4 of the DAA). Refer to previous Step-by-Step guides for generating histogram output and descriptives output for the assigned Unit 8 assignment variable.

Step 2. Generate SPSS output for the Shapiro Wilk test of normality. Select Analyze ( Descriptive Statistics ( Explore…

The Explore window will appear. Move the assigned Unit 8 assignment 1 variable into the Dependent List area. The “final” variable is used as an example below. Select the Plots button.

Select the “Normality plots with tests” option. Press Continue and OK.

Copy and paste the Tests of Normality in to Section 2 of the DAA and interpret it.

The Levene Test is generated as part of the SPSS t test output reported in Section 4 (discussed next). You do not have to provide the Levene Test output twice; just report and interpret it in Section 2 and the actual output will appear in Section 4.

DAA Section 4: Reporting of t Tests

DAA Section 4 involves generating the t test output and interpreting it. The examples variables of “lowup” (lower division = 1; upper division = 2) and “final” are shown below.

Step 3. Generate SPSS output for the t test. Select Analyze ( Compare Means ( Independent-Samples T Test…

The Independent-Samples T Test window appears. Move the assigned Unit 8 Assignment 1 dependent variable into the Test Variables window. Move the assigned Unit 8 assignment variable into the Group Variable window. Notice the (? ?). The values of the independent variable are assigned in the next step.

Press the Define Groups… button. Assign the corresponding values. Group 1 = 1. Group 2 = 2. Press Continue and OK.

The Independent Samples Test output appears. Copy and paste this output into Section 4 of the DAA and interpret it as assigned in the Unit 8 assignment instructions.