Applying statistics in the courtroom: a new approach for attorneys and expert witnesses

274 Pages·2001·1.143 MB·English

by  Phillip I. Good

APPLYING
STATISTICS
IN THE
COURTROOM
A New Approach
for Attorneys and
Expert Witnesses
Copyright 2001 by Chapman & Hall/CRC CRC Press LLC
APPLYING
STATISTICS
IN THE
COURTROOM
A New Approach
for Attorneys and
Expert Witnesses
Phillip I. Good
CHAPMAN & HALL/CRC
Boca Raton London New York Washington, D.C.
Copyright 2001 by Chapman & Hall/CRC CRC Press LLC
Library of Congress Cataloging-in-Publication Data
Good, Phillip I.
Applying statistics in the courtroom : a new approach for attorneys and expert witnesses
/ Phillip I. Good.
p. cm.
Includes bibliographical references and index.
ISBN 1-58488-271-9 (alk. paper)
1. Forensic statistics—United States. I. Title.
KF8968.75 .G66 2001
347.73′67—dc21 2001028695
Catalog record is available from the Library of Congress
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Copyright 2001 by Chapman & Hall/CRC CRC Press LLC
Preface
For the rational study of the law … the man of the future is the
man of statistics and the master of economics.
Oliver Wendell Holmes, 1897
We have written this text for two audiences with a single common goal:
to ensure attorneys and statisticians will work together successfully on
the application of statistics in the law.
To be effective in the courtroom, a statistician must be able to think
like a lawyer and present complex statistical concepts in terms a judge
can understand. Thus, we present the principles of statistics and probability,
not as a series of symbols, but in the words of jurists. Concepts take
precedence over formula.
Statisticians who may be skeptical of this approach should remember
the law is what judges say it is.
For the attorney, a change in point of view is also necessary. West has
no categories labeled “cohort analysis” or “sample size.” Sheppardize, but do
not expect to find cases that uphold or reverse the statistical points raised.
The opinions in this text are included for any or all of the following reasons:
(cid:1) They provide concise definitions of statistical concepts.
(cid:1) They provide lucid explanations of these concepts.
(cid:1) They illustrate the presentation of statistical evidence.
(cid:1) They reveal grounds on which a statistical argument may be
successfully attacked.
Two further caveats: our coverage is not meant to be complete. If we
write, “two other circuits have approved the use of statistical sampling,”
Copyright 2001 by Chapman & Hall/CRC CRC Press LLC
we do not mean to imply that other circuits have not approved it. Such
statements imply only that our research has been limited. Finally, we have
focused solely on the statistical issues in given cases. Many other issues
are involved in almost every instance and, frequently, these issues, not the
statistical ones, have formed the basis for a court’s ultimate determination.
Hopefully, this text will serve the attorney as a comprehensive guide
to the application of statistics and probability in jury selection, employment
discrimination, trademark disputes, criminal law, civil law, and product
liability. Sidebars and Chapters 13 and 15 indicate issues to raise during
discovery and possible lines of counterattack, as well as potential areas
of vulnerability.
This book is divided into four parts. The opening chapters concern
the relationship between a sample and the population from which it is
drawn. Chapter 1 describes the courts’ gradual acceptance of samples and
sampling methodology. Chapter 2 defines the representative random sam-
ple. Chapter 3 compares various sampling methodologies. Chapter 4 is
devoted to the use of descriptive statistics in the courtroom including
measures of central tendency, precision, and percentage.
Chapter 5 provides a brief introduction to probability. Chapters 6, 7,
and 8 describe the varying acceptance of probability-based testimony in
civil, criminal, and environmental hazard cases, respectively.
Chapter 9 summarizes the courts’ responses to how large a sample
must be. Chapter 10 addresses the same topic from the statistician’s
point of view and describes some simple procedures for testing sta-
tistical hypotheses. Chapter 11 describes correlation and regression of
two variables. Chapter 12 extends this discussion to multiple variables
and shows how the courts have applied multiple regression methods
in cases of alleged discrimination.
Chapter 13 is devoted to preventive actions that can be taken to stay
out of the courtroom and discusses the challenges that can be made to
bad statistics once inside. Chapter 14 prepares the statistician for some of
the twists and turns the trial process can take. Chapter 15 describes how
an attorney can make the most effective use of statistics and statisticians
at various points in the trial process and provides a set of questions on
data-related concerns for use during discovery.
I would like to express my gratitude to the following libraries for the
use of their facilities: the Orange County Law Library, the University of
San Diego Law Library, and the Whittier Law School Library. Without these
excellent community resources, this text would have been impossible.
Copyright 2001 by Chapman & Hall/CRC CRC Press LLC
Interpreting Case Citations
For those unfamiliar with legal research, here is a brief
explanation of case citations such as U.S. v. Two Bulls,
918 F.2d 56, 61 (8th Cir. 1990). This citation refers to a
decision handed down in 1990 by the court of appeals
for the Eighth Circuit which embraces the Dakotas,
Nebraska, Minnesota, Iowa, Missouri, and Arkansas. The
appeal was brought by federal prosecutors (the U.S.)
unhappy with the results of the earlier trial of Two Bulls
(a Navaho Indian). This decision was reported in Vol-
ume 918 of the second series of the Federal Reporter
beginning on page 56; the cited quotation will be found
on page 61.
Copyright 2001 by Chapman & Hall/CRC CRC Press LLC
Prologue: An Introduction
to the U.S. Court System
for the Statistician
The purpose of this prologue is to describe for the statistician the court
system in the U.S. and the roles the statistician will be expected to play.
The majority of the statistician’s participation will take place behind
the scenes as an advisor to the attorney. He or she may provide an
estimate or a significance level and be asked to comment on and find
weaknesses in the statistical procedures the attorney’s opponent has used
or is likely to use. The statistician’s work product may appear in court as
a portion of an attorney’s brief (written motion), or it may never appear
at all.
A trial is preceded by a series of pretrial motions and a process known
as discovery, in which depositions are taken and the facts of the case are
more or less agreed upon. The purpose of discovery is to reduce the time
actually spent in the courtroom and, hopefully, to bring both parties to
a settlement without having to hold a trial. Consider yourself a success if
your efforts as a statistician contribute to a pretrial settlement.1
As a statistician, you may be asked to provide testimony under oath
in the form of a deposition. This testimony will not be given in court and
may be taken in an attorney’s office or on neutral ground. You may be
asked to testify by the attorney who hired you originally or by the attorney
1 Assuming, of course, you don’t persuade the attorney you work for that he or she
has no case when, in fact, the case is an excellent one.
Copyright 2001 by Chapman & Hall/CRC CRC Press LLC
who is his or her opponent. In either case, you may be subject to a
detailed (and unpleasant) examination or cross-examination by the oppos-
ing attorney. You can get revenge of a sort by counseling your attorney
thoroughly so that he or she can subject the opposing party’s statistician
to an equally unpleasant afternoon of questions. In a third, relatively rare
alternative, you may be summoned and employed by a judge to act as
an impartial expert witness.
Many cases go to trial in a state or a federal court. During the trial, the
judge may be asked to rule on various points of law that arise. An example
would be to decide whether the results of a survey may be introduced in
court. To guide his or her ruling, the judge may review rules that his or
her own and higher courts have published, the published opinions of
appeals and higher courts (common law), statutes (laws passed by legis-
latures), and other sources of information he or she considers helpful.
A ruling made by a federal district court may be reviewed by a federal
circuit appeals court, and the appeals court ruling may be further reviewed
by the U.S. Supreme Court. Not all cases are subject to review; the Supreme
Court reviews only a handful of the appeals that come to it. A ruling by
the Supreme Court is binding on all federal courts. A ruling by a circuit
appeals court is binding only on the courts within its circuit, and its ruling
is subordinate to whatever the Supreme Court later decides.
A ruling by a state court may be reviewed by a state appeals court
and (depending on the state) may be reviewed subsequently by still higher
level courts in that state. A ruling by the highest state court is binding on
all the courts within that state, but it is not binding on the courts in other
states.2 Nor is a ruling in a federal court binding on any of the state courts.3
Decisions by state trial courts are almost never published and thus
cannot be cited by attorneys. Some federal trial court opinions are pub-
lished; most are not. Almost all appeals court and higher court opinions
are published. Trial court judges look to those opinions for guidance, and
we have looked to them for material on the application of statistics in
the courtroom.
2 Nonetheless, a judge in one state might well be interested in what the appeals
courts in other states have decided if a ruling on a particular point of law has not
yet been made in his or her own state.
3 The exception is an appeal of a state court decision based on an alleged violation
of federal law. An example would be the overturning by a federal court of a decision
in a state that did not allow African-Americans to serve on its juries.
Copyright 2001 by Chapman & Hall/CRC CRC Press LLC
The Author
Phillip Good, Ph.D., a graduate of the University of California at Berkeley’s
program in mathematical statistics and a paralegal, is the author of
12 published books including Permutation Tests (Springer, 1994, second
edition, 2000), and Resampling Methods (Birkhauser, 1999, second edition,
2001), as well as 34 scholarly publications, 12 published short stories, and
over 600 popular articles. A former Calloway Professor of Computer
Science at the University of Georgia, Division Head and Professor of
Biology and Physics at West Coast University, and Associate Professor of
Applied Mathematics at Claremont College, he has worked in the aero-
space, computer, energy, marketing, pharmaceutical, and telecommunica-
tion industries. He has worked with attorneys on cases involving audits,
jury selection, personal injury, and product liability.
Copyright 2001 by Chapman & Hall/CRC CRC Press LLC