Integrated Environmental Assessment and Management — Volume 15, Number 1—pp. 165–169
165
Book Reviews
LET THE EVIDENCE SPEAK: USING BAYESIAN
THINKING IN LAW, MEDICINE, ECOLOGY AND
OTHER AREAS
by Alan Jessop
Let the Evidence Speak by Alan Jessop provides a clear
and enjoyable discussion of how evidence and Bayesian
reasoning go hand in hand. This book makes Bayes
accessible by explaining why it is useful to know what
Bayes’ Rule is, how it can be used to solve problems, both
simple and complex, and how to communicate Bayesian
reasoning to a broad audience. Bayes’ Rule is not just an
equation for statisticians or data miners; it is “a way of
thinking,” as Jessop states, that helps determine how the
available evidence can revise previous beliefs in a
hypothesis. This book explains how Bayesian thinking is
useful for many different types of problems, from the
everyday to the uncommon. Overall, the case studies and
discussions provide a useful introduction on the advantages
of Bayesian thinking and Bayes’ Rule when weighing
evidence.
The book is well written and well organized, making it an
enjoyable read for both novices and advanced Bayesian
practitioners. Jessop gently introduces the components of
Bayes’ theorem in a manner that makes the reader forget
she is learning about a mathematical formula. Rather than
jumping into Bayes’ theorem as an overarching paradigm,
Jessop initially focuses on 1 part of the equation that
binds Bayesian and classical analysis—estimating and
interpreting likelihoods. The chosen examples and descriptions in this and other sections are a strong draw and
enhance understanding of the more advanced technical
subjects.
The book moves into Bayes’ theorem by introducing the
assumption of equal base rate probabilities. Incorporating
prior knowledge with Bayes’ theorem is elucidated
through base rates or contextual probabilities with
medical case studies (e.g., patient history). The discussion
Integr Environ Assess Manag 2019:165–169
SETAC Book Reviews Editor
Glenn Suter
US Environmental Protection Agency
26 Martin Luther King Drive
MC-A110
Cincinnati, OH 45268 USA
T 1-513-569-7808
F 1-513-569-7475
suter.glenn@epamail.epa.gov
includes cases in which base rates are wrongfully ignored
and in which they are difficult to estimate. In the final
sections, case studies from different fields are provided as
applications of Bayesian analysis including archaeology
(carbon dating), document analysis (authorship determination), and forestry. The emphasis is on the foundation
provided in earlier chapters and its relevance to more
complex problems, but advanced concepts are introduced, such as change point analysis, parameter estimation, and model testing. The final section provides an
example around a deceptively simple psychological
puzzle of how Bayesian analysis (and information theory)
can still provide insights when problems are fuzzy and
probabilities are difficult to estimate.
Jessop skillfully introduces important and initially daunting concepts. For example, Shannon entropy is first
introduced as a measure of surprise from receiving news
that the author’s favorite English football team had won a
difficult match. The first time the author hears the news, he
has a high level of surprise, but when subsequently
informed of the win, the surprise (and the information
content) is low. This leads into a discussion of the potential
“surprise” or information value of a medical test and how
entropy can be used as a measure of uncertainty and
information value of evidence from modifying prior
probabilities by the certainty the evidence can provide. In
another example, Jessop communicates the effects of
dependent variables through descriptions of gross domestic product predictions. If 2 banks copy each other’s
predictions (complete dependency), then there is no
increase in evidence value from receiving both reports
and the lack of evidence strength must be accommodated
in an assessment. The discussion of independence and
dependence issues with evidence in legal cases is also of
high interest.
One of the key contributions of this book is the authors’
development of a useful tool for assessing evidence
called the Bayes grid. Bayes grid is applied throughout
the book to calculate posterior probabilities. I can see
Bayes grids being adapted for meetings or group
settings, communicating evidence analysis, and instances
DOI: 10.1002/ieam.4109
C
2018 SETAC
166
Integr Environ Assess Manag 15, 2019—G Suter, Editor
in which simple and intuitive ways of calculating conditional probabilities are needed. There are no requirements
for remembering which permutation of Bayes’ theorem
is correct with a Bayes grid; only an understanding of
how to build the tables and transform numbers with
simple algebra. As stated in the book, Bayes grid will not
work on all problems, especially ones involving complex
model building or continuous parameter estimation,
but it does help to understand and approximate these
approaches.
By the end of the book, the point is made—Bayesian
analysis can be a powerful and usable aid for a diversity
of important problems involving information or evidence.
This is not to say the discussion of Bayesian analysis
is not practical or balanced. In 1 of my favorite sections
of the book, Jessop provides a nuanced discussion on
the use of Bayes’ theorem in the criminal court system
that incorporates multiple diverging perspectives.
The potential benefits of a Bayesian analysis are first
introduced through the actual case of Sally Clark, in which
a wrongful use of statistics by an expert witness led
to a conviction for murder. The errors that led to this
conclusion and their correction are clearly illustrated
through the application of a Bayes grid. But how and
whether to implement a Bayesian analysis in legal settings
is still an unresolved issue. The legal expert debates and
Jessop’s practical perspectives on the use of Bayes’ Rule
are important and could pertain to many jurisdictions and
settings.
Let the Evidence Speak does not provide the technical
background or guidance for choosing and using software
for running a Bayesian analysis for complex problems.
There are important topics that are not covered in
sufficient detail for a full perspective (such as parameter
estimation, the frequentist perspective, or Bayesian
networks). But I do not view this as a detraction. This
book provides a valuable resource for understanding
and communicating Bayesian reasoning to a broad
audience. Moreover, the information in this book provides a requisite foundation for designing, comprehending, and critically evaluating a complex Bayesian analysis.
I will recommend Let the Evidence Speak to colleagues
who are interested in learning about how Bayesian
thinking works, looking for a very useful tool for teaching
or rapidly applying Bayes’ Rule, in need of a handy
reference on the strong insights a Bayesian analysis can
provide, or wanting a technical book that is just plain
fun to read.
Disclaimer—The views expressed are those of the author
and do not necessarily represent the views or policies of
the US Environmental Protection Agency.
2018. eBook. 224 pp. ISBN 978-3-319-71392-2. $29.99.
Springer International Publishing AG, Cham, Switzerland.
John Carriger
US Environmental Protection Agency
Integr Environ Assess Manag 2019:165–169
ANTICOAGULANT RODENTICIDES AND WILDLIFE
edited by Nico W van den Brink, John E Elliott, Richard F Shore,
and Barnett A Rattner
Warfarin and related rodenticides are commonly recognized as posing significant risks to nontarget species. Their
mechanisms of action are common to all vertebrates, and
they are sufficiently persistent to cause effects on various
nontarget species due to primary exposures in bait and
secondary exposure from scavenging of animals killed or
debilitated by primary exposures. However, their use
continues because rodents are such important pests and
because there are few good alternatives.
This book is an excellent summary of the risks of
anticoagulants to wildlife, edited and authored by experts.
The 14 chapters do a good job of covering the subject,
with chapter topics ranging from use and exposure,
through toxicology, epidemiology, mitigation, regulation,
and potential alternatives. Some topics are missing, but that
is inevitable because the editors are limited by their author
pool and available information. For example, there is a
chapter on the diagnosis of effects in birds but not one for
mammals, and a chapter on risk modeling for nontarget
small mammals but not for secondarily poisoned birds
and mammals. Environmental chemistry is given minimal
attention because transport and fate play minimal roles in
wildlife risks from these compounds.
Given the long history and common use of anticoagulant
rodenticides, the information gaps identified by the authors
are remarkable. Little is known about relative sensitivities to
these agents and, even though tissue residues are commonly
monitored, the relation between residues and effects are
poorly understood. The importance of this knowledge gap is
highlighted by the statement that “58% (2414 out of 4187) of
predators analyzed in world-wide monitoring studies have AR
tissue residues.” Further, contrary to expectations, shrews
and hedgehogs commonly bear residues. Although mitigation is discussed at length, alternatives are not. For example,
gene drives are being discussed for eradication of rodents on
islands. That technology could be more effective than
anticoagulants, would avoid the poisoning of native wildlife,
wileyonlinelibrary.com/journal/ieam
C
2018 SETAC