Statistical methods in environmental epidemiology

Statistical Methods in

ENVIRONMENTA L

EPIDEMIOLOG Y

- \ J

u

OXFOR D

Statistica l Method s

i n Environmenta l

Epidemiolog y

Duncan C. Thomas

D AI HOC THA I NGUYEN

TRUNGTAM HOC LIEU

OXFOR D

UNIVERSITY PRESS

OXFOR D

UNIVERSITY PRESS

Great Clarendon Street, Oxford OX2 6DP

Oxford University Press is a department of the University of Oxford.

It furthers the University's objective of excellence in research, scholarship,

and education by publishing worldwide in

Oxford New York

Auckland Cape Town Dares Salaam Hong Kong Karachi

Kuala Lumpur Madrid Melbourne Mexico City Nairobi

New Delhi Shanghai Taipei Toronto

With offices in

Argentina Austria Brazil Chile Czech Republic France Greece

Guatemala Hungary Italy Japan Poland Portugal Singapore

South Korea Switzerland Thailand Turkey Ukraine Vietnam

Oxford is a registered trade mark of Oxford University Press

in the UK and in certain other countries

Published in the United States

by Oxford University Press Inc., New York

© Duncan C. Thomas 2009

The moral rights of the author have been asserted

Database right Oxford University Press (maker)

First published 2009

All rights reserved. No part of this publication may be reproduced,

stored in a retrieval system, or transmitted, in any form or by any means,

without the prior permission in writing of Oxford University Press,

or as expressly permitted by law, or under terms agreed with the appropriate

reprographics rights organization. Enquiries concerning reproduction

outside the scope of the above should be sent to the Rights Department,

Oxford University Press, at the address above

You must not circulate this book in any other binding or cover

and you must impose this same condition on any acquirer

British Library Cataloguing in Publication Data

Data available

Library of Congress Cataloging in Publication Data

Data available

Typeset by Newgen Imaging Systems (P) Ltd., Chennai, India

Printed in Great Britain

on acid-free paper by

CPI Antony Rowe, Chippenham, Wiltshire

ISBN 978-0-19-923289-5 (hbk)

978-0-19-923290-1 (pbk)

10 98765432 1

T o m y father, a rol e mode l fo r m y career

A n y m y mother, wh o taugh t me t o writ e

Content s

Preface xiv

1 A tale of two exposures 1

The ionizing radiation tale 3

The air pollution tale 11

2 Basic epidemiologic study designs 19

Experimental 19

Descriptive 20

Geographic comparisons 20

Temporal comparisons 21

Prevalence surveys 21

Analytical 22

Cohort study design 23

Case-control study design 24

Nested case-control and case-cohort designs 28

Interpretation of epidemiologic associations 29

3 Basic statistical methods 33

Basic probability theory 33

Probability distributions used in epidemiology 36

Binomial distribution 36

Poisson distribution 36

Normal distribution 38

Chi square distribution 38

Measures of disease frequency and risk 39

Absolute risk 40

Risk 40

Rates 41

Survival analysis 41

Relative risk 43

Case-control studies 45

viii Contents

Cohort studies 48

Attributable risk and other measures of

public health impact 49

Interaction 51

Basic principles of statistical inference 52

4 Multivariate models 55

Linear regression for continuous data 56

Multivariate models for binary data 57

Logistic regression 57

Binomial regression for grouped binary data 62

Censored survival analysis 63

Nested case-control studies 68

Poisson regression 70

Extra-Poisson variation 73

Principles of ML inference 73

Bayesian methods 80

The general linear model 82

Generalized estimating equations 83

Missing data 85

Missingness models 86

Missing data imputation 87

Missing indicator methods 90

5 Some special-purpose designs 92

Two-phase case-control designs 92

Counter-matching 99

Case-distribution studies 103

Case-crossover design 104

Poisson process model for recurrent events 105

Case-specular design 106

Case-only and case-parent-triad designs 108

6 Modeling exposure-time-response relationships 110

Basic dose-response models 110

Parametric models 111

Nonparametric models 115

Incorporating temporal modifiers 124

Extended exposure histories 128