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

Determining Level of Alcohol and Drug Use

As in virtually every field of study, there are disagreements. In the fields of substance abuse prevention and treatment, there are different approaches to measuring alcohol and drug use. Some argue that amount consumed is a better measure of drug use/abuse than frequency of use. There is certainly merit to this argument.

Many people would agree that an adult having a glass of wine per day is O.K, provided she is not pregnant! However, an adult drinking 30 glasses of wine in one day is definitely NOT O.K. If you only look at number of days used per month, the moderate drinker would be represented as "30 days used" and the binge drinker could be represented as "1 day used."

Looking at quantity of substances used presents its own set of challenges. Depending on the substance, it may be difficult to establish amount. For example, kids who smoke marijuana often smoke in a group. If four kids passed around three joints, it would be hard to say with certainty how much marijuana each kid got. That would depend on how much he or she took, the size of the joint, and the concentration of marijuana in each joint. Added to that, you would be relying on what each kid actually remembered smoking!

Similarly, quantity of alcohol depends on the concentration of alcohol (% proof), amount of alcohol, and size of the glass. For example, a cocktail could be a shot of gin mixed with tonic, a double shot of vodka mixed with orange juice, or a martini made with a shot of gin and a shot of vermouth. A beer could mean anything from a 12-ounce bottle to a 40-ounce can.