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 4: Calculate the mean for the sum of the differences between posttest scores and pretest scores ().

Divide 33 by 50. The number of participants, 50, is called the n value.

= 33/50 = 0.66

You will use this value in step 10.