Dependent samples t-test
We use this t-test when we have a repeated measures design such as the same sample completes a pre and post-test and we want to know if there is a difference from one test to the other.
Ø Go to analyze, compare means, paired sample t-test
Ø Select two variables and move into box
Ø Click on OK
Ø The output will give you means for each trial (or pre-post test measure) as well as the t-statistic and significance level
Let's try a few using the data below. Be sure to attach your printouts and answer the questions below.
- First, gave a independent sample t-test for gender (IV) and pretest scores (DV)
Were there significant gender differences? How do you know? Interpret the results statistically and in words.
- Then give a independent sample t-test for gender (IV) and posttest scores (DV)
Were there significant gender differences? How do you know? Interpret the results statistically and in words.
- Now, give a paired (dependent) sample t-test for pretest and posttest scores.
Were there two scores significantly different? How do you know? Interpret the results statistically and in words.
Data Set Homework 2 (*note 1 = males, 2 = females)
Gender Pretest Posttest
1.00 50.00 80.00
1.00 50.00 70.00
1.00 80.00 70.00
1.00 80.00 50.00
1.00 70.00 50.00
1.00 70.00 50.00
1.00 60.00 60.00
1.00 60.00 80.00
1.00 90.00 80.00
1.00 90.00 90.00
1.00 90.00 80.00
1.00 80.00 90.00
1.00 80.00 90.00
1.00 70.00 70.00
1.00 70.00 80.00
1.00 50.00 80.00
1.00 50.00 70.00
1.00 50.00 70.00
1.00 60.00 60.00
1.00 70.00 80.00
2.00 50.00 70.00
2.00 40.00 50.00
2.00 40.00 80.00
2.00 70.00 80.00
2.00 50.00 70.00
2.00 50.00 80.00
2.00 50.00 90.00
2.00 60.00 90.00
2.00 70.00 90.00
2.00 40.00 80.00
2.00 40.00 80.00
2.00 30.00 70.00
2.00 30.00 70.00
2.00 50.00 60.00
2.00 60.00 80.00
2.00 40.00 80.00
2.00 70.00 80.00
2.00 50.00 70.00
2.00 60.00 70.00
2.00 70.00 90.00