Book excerpt: Intended to provide a basic understanding not only of how to design and implement social experiments, but also of how to interpret their results once they are completed, author Larry L. Orr's Social Experiments is written in a friendly, how-to manner. Through the use of illustrative examples, how-to exhibits and cases, and boldface key words, Orr provides readers with a grounding in the experimental method, including the rational and ethical issues of random assignment; designs that best address alternative policy questions; maximizing the precision of the estimates; implementing the experiment in the field; data collection; estimating and interpreting program impacts, costs, and benefits; dealing with potential biases; and the use and misuse of experimental results in the policy process. This book will be useful not only to those who plan to conduct experiments, but also to the much larger group who will, at one time or another, want to understand the results of experimental evaluations.