T Test Procedure in SPSS Statistics

The eight steps below show you how to analyse your data using an independent t-test in SPSS Statistics when the six assumptions in the previous section, Assumptions, have not been violated. At the end of these eight steps, we show you how to interpret the results from this test. If you are looking for help to make sure your data meets assumptions #4, #5 and #6, which are required when using an independent t-test, and can be tested using SPSS Statistics, you can learn more here.

• Click Analyze > Compare Means > Independent-Samples T Test... on the top menu, as shown below:

  

  Published with written permission from SPSS Statistics, IBM Corporation.

  You will be presented with the Independent-Samples T Test dialogue box, as shown below:

  

  Published with written permission from SPSS Statistics, IBM Corporation.

• Transfer the dependent variable, Cholesterol, into the Test Variable(s): box, and transfer the independent variable, Treatment, into the Grouping Variable: box, by highlighting the relevant variables and pressing the  buttons. You will end up with the following screen:

  

  Published with written permission from SPSS Statistics, IBM Corporation.

• You then need to define the groups (treatments). Click on the  button. You will be presented with the Define Groupsdialogue box, as shown below:

  

  Published with written permission from SPSS Statistics, IBM Corporation.

• Enter "1" into the Group 1: box and enter "2" into the Group 2: box. Remember that we labelled the Diet Treatment group as 1 and the Exercise Treatment group as 2.

  

  Published with written permission from SPSS Statistics, IBM Corporation.

  Note: If you have more than 2 treatment groups in your study (e.g., 3 groups: diet, exercise and drug treatment groups), but only wanted to compared two (e.g., the diet and drug treatment groups), you could type in 1 to Group 1: box and 3 to Group 2:box (i.e., if you wished to compare the diet with drug treatment).

• Click the  button.

• If you need to change the confidence level limits or change how to exclude cases, click the  button. You will be presented with the following:

  

  Published with written permission from SPSS Statistics, IBM Corporation.

• Click the  button. You will be returned to the Independent-Samples T Test dialogue box.

• Click the  button.