CONTENTS

Table of Contents
Introduction

1. Descriptive Statistics in Evaluation
2. Subgroup Analysis
3. Variable - Are They Related?
4. Correlation
5. The t-Test of Difference Between Means

Supplements
Resources
Glossary

Wading Through the Data Swamp:
Program Evaluation 201

The t-Test of Differences Between Means:
Paired Sample t-Test for Participant Pre- and Posttests

Step 6: Square the differences between posttest scores and pretest scores and add the results.

Square each X score (X = Post - Pre). Then add the squared scores that you calculate (X²).

You will use this value in step 7 as part of the sum of squares calculation.