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:
Independent Samples t-Test for Pretest Data

Step 6: Square each person's score for both groups and sum the squared scores.

The first task is to square each person's pretest score. For example, participant 1 had a pretest score of 0. The square of 0 is 0. comparison group member 1 had a pretest score of 5. The square of 5 is 25. Once you have the squares of all the scores for each group, you add them up for each group.

The sum of the squared scores for the participant group is 278. The sum of the squared scores for the comparison group is 297. The sum of the squared scores is represented by the formula (scores)². These numbers will be used in step 7, the sum of squares calculation.