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 3: Subtract the pretest scores from the posttest scores and add the results.

For the 50 participants, the result of subtracting the pretest scores and adding the results is 33.