Which statistical test to use using pretest and post test data? I am trying to analyze data which there were two groups, control and treatment.  Both groups were given a pre-test and post-test.  The control group received differentiated instruction and the control group received teacher directed instruction.  Trying to find out if there is a difference in student achievement. I am trying to use SPSS program
 A: You're looking for a mixed model ANOVA, which is called a "repeated measures ANOVA" in SPSS. Go to Analyze > General Linear Model > Repeated Measures. 
Label your "Within-Subject Factor Name:" as prepost and specify 2 levels. 
That's because your pre and post measurements are going to be treated as repeated measurements in the mixed model ANOVA. The two levels correspond to pre-treatment and post-treatment. 
Click "Add" then click "Define"
Under "Within-Subjects Variables (prepost):" You'll move over your pretreatment variable, then your postreatment variable. 
Under "Between-Subjects Factor(s):" you can move over your grouping variable. This is the variable that indicates which subject is in the control vs treatment group. 
In addition, under between subjects factors, you can feel free to include any other categorical variables that you want to account for. For instance, you might include gender or race, but you would not include age (because age is continuous). 
Under covariates, you may include any continuous variables you want to control for, like age. 
On the side bar, you can use the Options button to select descriptive statistics. 
Once everything is in place, just click OK.  
