Applying Statistics in the Courtroom

Article excerpt

Phillip I. Good

Chapman & Hall/CRC, Boca Raton, Florida, 2001

ISBN 1-58488-271-9

The author's stated purpose in writing this book is "to ensure attorneys and statisticians will work together successfully on the application of statistics in the law." To this end, he has aimed this book squarely at these two groups. The book is written at a level appropriate for those statisticians and lawyers who know very little about the other's discipline. This text is largely successful at providing an introductory overview to the attorney and the statistician which will prepare them for entering the unknown territory of the other group. The approach in this book is to use selected citations from court opinions to illustrate various points concerning acceptance (and rejection) of statistics in the courtroom. For the statistician who is unfamiliar with legal proceedings, the book provides specific and sound advice on methods for presenting statistical concepts in terms that a judge would understand. Similarly, attorneys who are seeking to use supporting statistics in a variety of legal settings will find many of the ideas presented useful. However, statisticians who are looking for technical details concerning legal use of statistics or attorneys who need an exhaustive review of pertinent cases for preparation of briefs will likely be disappointed by this book. The strength of this book is that it contains practical and useful advice on the use of statistics and probability in such areas as jury selection, discrimination, trademark disputes, criminal law, civil law, and product liability.

The book is divided into four parts and fifteen chapters. The first part, entitled Samples and Populations, consists of four chapters concerning methods of sample selection and the use of descriptive statistics. Chapter 1 discusses the definition of samples and methods of selecting representative samples from the point of view of the court. Chapter 2 provides a legal definition of the representative random sample. Chapter 3 compares sampling methodologies and contains useful advice concerning the proper use of surveys. Chapter 4 discusses the typical methods for presenting easily understood descriptive statistics. The statistician might find Chapter 4 oversimplified until he or she realizes the limited level of detail that can be understood by most jurors and some attorneys or judges.

The next four chapters form a section entitled Probability. Chapter 5 provides a brief, non-mathematical introduction to probability. Chapters 6 through 8 describe the various approaches to the use of probabilities that have been accepted in civil, criminal, and environmental cases, respectively. There is a major emphasis throughout these chapters on the difference between fact-based probabilities and estimates. The discussion in Chapter 6, Criminal Law, of the use of probabilities and particularly the legal requirements for multiplication of probabilities in the well-known People v. Collins case and the Wayne Williams trial, is particularly interesting. Those statisticians unfamiliar with courtroom procedures will either be fascinated or confounded by the variations in what has been accepted or rejected by various courts, and they would do well to heed the warning that "the law is what judges say it is."

The third group of four chapters is entitled Hypothesis Testing and Estimation. …