Dental statistics made easy

213 Pages·2017·2.66 MB·English

by  Smeeton

DENTAL
STATISTICS
MADE EASY
Third Edition

DENTAL
STATISTICS
MADE EASY
Third Edition
NIGEL C. SMEETON

Centre for Research in Primary and Community Care
University of Hertfordshire, UK
and
Division of Imaging Sciences and Biomedical Engineering
King’s College, London, UK
CRC Press
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Library of Congress Cataloging-in-Publication Data
Names: Smeeton, N. C., author.
Title: Dental statistics made easy / Nigel C. Smeeton.
Description: Third edition. | Boca Raton, FL : CRC Press, [2016] | Includes
bibliographical references and index.
Identifiers: LCCN 2016022440| ISBN 9781498775052 (pbk. : alk. paper) | ISBN
9781498775069 (e-book) | ISBN 9781498775083 (e-book) | ISBN 9781498775076
(e-book)
Subjects: | MESH: Statistics as Topic--methods | Dental Research--methods
Classification: LCC RK52.45 | NLM WU 20.5 | DDC 617.60072/7--dc23
LC record available at https://lccn.loc.gov/2016022440
Visit the Taylor & Francis Web site at
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Contents
Preface to the Third Edition vii
Preface to the Second Edition xi
Preface to the First Edition xiii
1 Introduction 1
2 Planning a Study 9
3 Types of Study in Dental Research 23
4 Sampling 31
5 Randomized Controlled Trials 37
6 Ethical Considerations 47
7 The Normal Distribution 55
8 Diagnostic Tests 59
9 Sampling Variation 69
10 Introduction to Hypothesis Tests 81
11 Comparing Two Means 89
12 Dealing with Proportions and Categorical Data 97
13 Comparing Several Means 107
14 Regression, Correlation, and Agreement 117
15 Non- Normally Distributed Data 129
16 The Choice of Sample Size 135
v
vi CONTENTS
17 Evidence- based Dentistry 141
18 Statistical Refereeing 149
Appendix 159
Solutions to Exercises 169
References 187
Index 191
Preface to the Third Edition
My background in teaching dental statistics goes back to the early
1990s, when I became engaged in introducing the basics of study
design and data analysis to undergraduate dental students at the very
start of their professional training. This experience was supplemented
by visits to dental practical sessions (complete with lab coat) where I
was able to see fi rst hand the collection of data such as salivary fl ow
rates. At that time, medical students were able to choose from a range
of medical statistics texts, whereas there were few introductory statistics
books written specifi cally with dental training in mind. In addition,
it was not uncommon for dental students to feel challenged by the
mathematical approach then in common use.
This gap in student learning resources was initially addressed
through the development of tailored course notes that included guided
tutorials along with detailed solutions. In addition, students were
introduced to dental journal literature through articles on major issues
such as the fl uoridation of public water supplies and dental health pro-
vision in areas of deprivation. The material was well received by dental
students and staff alike, and it became clear that there was a need for a
textbook in dental statistics which cut through the algebra and focused
directly on the issues that bring dentistry and statistics together. The
encouragement of my colleagues and dental students at King’s College
London brought about the publication of Dental Statistics Made Easy
in 2005, with a second edition in 2012.
The needs of qualifi ed dentists and those engaged in dental research
have not been overlooked. The collection and interpretation of infor-
mation is essential in, for instance, the development of new treatments,
the delivery of dental care in the community, and the administration of
patient records at a dental practice. This book provides an introduction
to how this information is collected and analyzed, and the role that
academic publication plays in the dissemination of research fi ndings.
There is an emphasis on underlying principles, illustrated by draw-
ing from published dental studies and realistic examples rather than
through recourse to algebraic formulae.
The fi rst chapter explains why familiarity with dental statistics is
vii
viii PREFACE TO THE THIRD EDITION
important. The next chapters provide a broad overview of study design.
Attention is given to the use of pilot studies, public and patient involve-
ment in research, and ethical considerations, as well as to the common
types of design and most widely used methods of sampling. The reader
is then introduced to the Normal distribution, diagnostic testing, and
the concept of sampling variation. Subsequent chapters cover the
analysis of dental data, with an emphasis on the use of null hypotheses
and the interpretation of confi dence intervals (details of some of the
calculations are provided in the Appendix). The book concludes with
a description of how a review of the dental literature can be applied to
modify everyday dental practice, followed by an account of the process
involved in the development of a dental paper from the initial drafting
of a report to its eventual publication in an academic journal.
This text has been written with a wide audience in mind, including
dental students, qualifi ed dentists, those engaged in dental research,
and health- care professionals in general. No previous knowledge of
statistics is required, and, importantly for readers who are not dentists,
the illustrative examples are accessible to those involved in other areas
of health care. Its style makes the book suitable not only as a class
text but also for self-d irected learning. The main text provides a gentle
introduction to dental statistics, with exercises and solutions available
for readers taking an in-d epth approach. The numerous key messages
allow the time-p ressured dentist to benefi t from a superfi cial reading
and enable the most important principles to be located quickly. The
articles used in the book, along with the associated cited and citing
papers, will aid in identifying up-t o- date subject-s pecifi c literature for
student dissertations, library projects, and dental research.
NEW TO THIS EDITION
Some of the features of the present edition are the following:
➤ A new chapter on evidence- based dentistry. This material
covers the “why” and “how” of systematic reviews along
with a very basic introduction to meta- analysis. Emphasis is
placed on sources of information, the hierarchy of research
and the concept of research quality. This chapter also covers
the neglected area of publications in languages other than
English. An intriguing question that has received scant
attention is addressed: Do dentists actually implement what
they discover through evidence- based dentistry in their
routine dental care?
PREFACE TO THE THIRD EDITION ix
➤ The selection of dental journal articles used in the examples and
exercises has been broadened and updated. The perspective of the
book is much more international, particularly, but not exclusively,
with regard to the United States, and examples have been drawn
from a range of cultures around the world.
➤ The assumption of independence of observations required for
most basic statistical techniques has been highlighted.
➤ The conduct of pilot studies is explained in greater detail. In
addition, the use of public and patient involvement (PPI) in
research is described as funding organizations increasingly expect
proposed studies to include PPI input.
➤ In the description of cohort studies, retrospective as well as
prospective designs are discussed.
➤ Cluster randomized trials have been included as part of the
material on randomized controlled trials.
➤ In the comparison of several means, a caution is given regarding
the use of the Bonferroni technique.
➤ Illustrative examples have been modifi ed. In part, this is to ensure
that the data are appropriate for the statistical methods described.
In addition, a caution has been given regarding current opinion
on the benefi ts of water fl uoridation. Increasing public concern
regarding patient home to dental practice distance explains the
choice of this issue for several examples.
ACKNOWLEDGMENTS
I wish to thank the many readers and reviewers who have provided
detailed constructive feedback on the earlier editions, and my col-
leagues at the Centre for Research in Primary and Community Care,
University of Hertfordshire, for their encouragement in my commit-
ment to making statistics accessible to all. Any imperfections in the
text are, of course, my responsibility.
Nigel Smeeton
August 2016