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

Steps for Calculating an Independent Samples t-Test for Posttest Data

• Step 1: State null hypothesis
• Step 2: Choose a significance level
• Step 3: Determine the difference in means between the two groups
• Step 4: Sum the scores of the pretest for both groups
• Step 5: Square the sum of the scores for both groups
• Step 6: Square each person's score for both groups and sum the squared scores
• Step 7: Complete the sum of squares (SS) calculation
• Step 8: Calculate the degrees of freedom
• Step 9: Calculate the combined variance
• Step 10: Use the t-test formula
• Step 11: Compare the calculated t-value with the critical t-value found in the table