Question

Mary, a colleague of yours, wants to test the effectiveness of a new lesson plan on two different groups of students. She wants to perform a t-test, but she is not sure whether to use a paired or unpaired test. Base on the information provided, how would you advise your colleague? If she asked you to perform the calculation for her, how would you use SPSS to do so? Create data in SPSS and run it as an example. I do not know how to set up the groups in SPSS.

Answer 1

Let us assume the two groups data:

Group A 26,21,22,26,19,22,26,25,24,21,23,23,18,29,22

Group B 18,23,21,20,20,29,20,16,20,26,24,25,17,18,19

This is an Independent Samples t-test because there are two different groups of students.

Enter the data into SPSS.

Name the variables.

Go to Group variable values and name the groups.

Enter Value = 1 & Label = Group A.

Enter Value = 2 & Label = Group B.

Go to the Independent-Samples T Test.

Go to Define Groups.

Click Continue and click OK.

The output is:

Since the P-value = 0.397 is greater than the significance level, we will assume that Equal variances not assumed for the data.

The hypothesis being tested is:

H₀: µ₁ = µ₂

H₁: µ₁ ≠ µ₂

The test statistic is 1.716.

The df is 26.774.

The P-value is 0.098.

Since the p-value (0.098) is greater than the significance level (0.05), we cannot reject the null hypothesis.

Therefore, we cannot conclude that there is a significant effect of a new lesson plan on two different groups of students.