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 7: Complete the sum of squares (SS) calculation.

The sum of squares is the sum of squared deviations from the mean. The calculation actually involves a bit of subtraction, even though it's called a sum. Don't worry about why. It's just part of the formula.

SS = 231 - 21.78 = 209.22