Statistics in the Courtroom
Chapman & Hall/CRC, Boca Raton, Florida, 2001
Counterterrorism and Forensic Science Research Unit
Federal Bureau of Investigation
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.
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.
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."
third group of four chapters is entitled Hypothesis Testing and
Estimation. Chapters 9 and 10 discuss how large a sample must be
from the perspectives of the court and the statistician, respectively.
Chapter 10 contains a brief overview of simple statistical procedures
for testing hypotheses. Chapter 11 describes correlation and regression
of two variables. Chapter 12 provides a similar discussion of multiple
variables. The emphasis in this chapter is on the legal acceptance
of multiple regression methods in cases of alleged discrimination.
readers will find the final section, Applying Statistics in the
Courtroom, to be the most practical and useful portion of this book.
Chapter 13 describes preventative actions that can be taken to reduce
the need to go to the courtroom and challenges that can be presented
when questionable statistics are used by the opposing expert. Chapter
14 provides the statistician with a blow-by-blow description of
the trial process, should the procedures in Chapter 13 fail to keep
him or her out of the courtroom. Chapter 15, Making Effective Use
of Statistics and Statisticians, is written for the attorney to
assist in making proper and effective use of statisticians and statistical
evaluation of evidence. This chapter is particularly useful in that
it contains a list of questions that lawyers can use during discovery
and to guide the testimony of a statistician.
reviewer is a forensic chemist, and because many of the readers
of Forensic Science Communications are forensic scientists,
a review of this book from that perspective seems in order. I opened
a book with the title Applying Statistics in the Courtroom
hoping to find practical advice on technical methods for the statistical
interpretation of physical evidence. Dr. Good is a recognized expert
with excellent credentials as both a statistician and a scientist.
However, he chose to target this book at an audience that does not
include the forensic scientist. Forensic scientists might find this
book interesting in that it applies statistical concepts that we
frequently use to situations that are likely to be unfamiliar to
us, such as the application of sampling concepts to jury selection.
However, this book will disappoint those hoping to find enlightenment
as to how to apply statistics to thorny probability problems concerning
Statistics in the Courtroom is probably most useful to attorneys
who can use the lists of questions and advice on the application
of statistics to make effective use of statisticians in writing
briefs, to guide pretrial conversations with their statisticians,
and to produce effective courtroom testimony that is understandable
to judges and jurists. Statisticians will find the advice given
to be useful until they have entered the legal arena a few times,
either by testifying, assisting in the writing of briefs, or preparing
cases. After that, they will likely find what approaches work best
for them and might refer back to this book only when they are faced
with a type of case that they have not previously encountered. This
book is easily readable and follows the style of the other familiar
CRC publications on various aspects of criminal sciences.
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