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

Module Content Objectives Background Variables - Are They Related? Hypotheses Research Questions Levels of Measurement What Is Chi-square? Contingency Tables Marijuana Use Chi-Square Calculations Continued for Marijuana Use (steps 7-10) Alcohol Use Chi-Square Calculations for Alcohol Use Continued (steps 7-10) Chi-Square Applet Lessons Learned: What Jack Should Have Asked His Evaluator What Did Jack Learn About His Program From These Analyses? How Can Jack Use This Statistical Information To Improve His Program? How Can Jack Use This Statistical Information To Better Promote His Program? Module 3 Quiz

Levels of Measurement

Variables are measured in different ways. How they are measured determines which statistical tests can be used.

Below are the different levels:

Nominal-level variables categorize qualitative differences. There is no quantitative meaning. For example, drug use can be a nominal variable. You may ask the participants in your program if they have used drugs in the past 30 days, "yes" or "no." You cannot say that yes is twice as much as no.

Have you used marijuana in the last 30 days?
(yes or no)

Ordinal-level variables are attributes that may be logically rank ordered. Each attribute represents more or less of the variable. For example, client satisfaction would logically be ordered from lesser satisfaction to greater satisfaction.

             How satisfied are you with the program?
 <----------------------------------------------------->

  Not at all              Somewhat                   Very

Interval-level variables have points at equal intervals. For example, a 1-year difference is always the same whether you are 10 or 50 years old. However, with interval-level variables, there is no true zero.

What is your age?
__13
__14
__15
__16

Ratio-level variables have equal intervals between the attributes and are based on a true zero point.

How many siblings do you have? __________