A DICTIONARY Epidemiology Fifth Edition Edited Miquel Porta REA A HANDBOOK SPONSORED BY THE LEA
Dictionary Epidemiology Fifth edition Edited for the International Epidemiological Association Miquel Porta Professor of Preventive Medicine Public Health School of medicine, Universitat Autonoma de barcelona Senior Scientist, Institut Municipal d Investigacio Medica Bare Adjunct Professor of Epidemiology, School of Public Health University of North Carolina at Chapel Hill Sander greenland John M. Last OXFORD UNIVERSITY PRESS
A Dictionary of Epidemiology of Fifth Edition Edited for the International Epidemiological Association by Miquel Porta Professor of Preventive Medicine & Public Health School of Medicine, Universitat Autònoma de Barcelona Senior Scientist, Institut Municipal d’Investigació Mèdica Barcelona, Spain Adjunct Professor of Epidemiology, School of Public Health University of North Carolina at Chapel Hill Associate Editors Sander Greenland John M. Last 1 2008
OXFORD UNIVERSITY PRES Oxford University Press, Inc, publishes works that further Oxford Universitys objective excellence th scholarshi p, and education Oxford New York Auckland Cape Town Dar es Salaam Hong Kong Karachi Kuala Lumpur Madrid Melbourne Mexico City Nairobi Shanghai Taipei Toronto With offices in Argentina Austria Brazil zech Republic France Greece Guatemala Hungary Italy Poland Portugal Singapore Copyright o 1983, 1988, 1995, 2001, 2008 International Epidemiological Association, Inc. Published by Oxford University Press, Inc 198 Madison Avenue. New York. New York 10016 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, ithout the prior permission of Oxford University Press. This edition was prepared with support from Esteve Foundation(Barcelona, Catalonia, Spain) Library of Congress Cataloging-in-Publication Data dictionary of epi edited for the International Epidemiological Association by Miquel Porta; associate editors, John M. Last.[ et al. ]-5the p cm. Includes bibliographical references and index ISBN978-0-19-5314496ISBN978-0-19-531450-2(pbk) 1. Epidemiology-Dictionaries I Porta, Miquel- I. International Epidemiological Association. A651D5532000 614403-dc2100-037504 246897531 Printed in the United States of America
Oxford University Press, Inc., publishes works that further 1 Oxford University’s objective excellence in research, scholarship, and education Oxford New York Auckland Cape Town Dar es Salaam Hong Kong Karachi Kuala Lumpur Madrid Melbourne Mexico City Nairobi Shanghai Taipei Toronto With offi ces in Argentina Austria Brazil Chile Czech Republic France Greece Guatemala Hungary Italy Japan Poland Portugal Singapore South Korea Switzerland Thailand Turkey Ukraine Vietnam Copyright © 1983, 1988, 1995, 2001, 2008 International Epidemiological Association, Inc. Published by Oxford University Press, Inc. 198 Madison Avenue, New York, New York 10016 www.oup-usa.org 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, electronic, mechanical, photocopying, recording, or otherwise, without the prior permission of Oxford University Press. This edition was prepared with support from Esteve Foundation (Barcelona, Catalonia, Spain) (http://www.esteve.org) Library of Congress Cataloging-in-Publication Data A dictionary of epidemiology / edited for the International Epidemiological Association by Miquel Porta; associate editors, John M. Last . . . [et al.].—5th ed. p. cm. Includes bibliographical references and index. ISBN 978–0-19–531449–6 ISBN 978–0-19–531450–2 (pbk.) 1. Epidemiology—Dictionaries. I. Porta, Miquel– II. International Epidemiological Association. RA651.D553 2000 614.4′03—dc21 00–037504 2 4 6 8 9 7 5 3 1 Printed in the United States of America on acid-free paper
Foreword TO WRITE A DICTIONARY IN ANY SCIENTIFIC DISCIPLINE IS A RISKY ENDEAVOR. BECAUSE scientists often disagree. The nature of science is not to reach consensus but to advance our knowledge by bringing conflicting ideas to critical examinations. That is true also for how we define the concepts we use. No dictionary will ever be able to satisfy all, nor should it try to he aim of the International Epidemiological Association(IEA)in cosponsor- ing this dictionary in its more than 20 years history has been to facilitate commu- nication among epidemiologists--to develop a"common language"to the extent that this is possible. We need a common language when we write papers, teach and communicate findings to the public This“ common lar nguage anges over time, as anybody can see by reading the successive editions of this dictionary. The language changes because our understanding of the concepts changes over time and new research options bring forward From the iea. we want to thank john Last for his tremendous achievements as editor of the dictionary, and we are happy to welcome Miquel Porta as the new editor. Miquel has provided the smooth transition we were looking for, and we are pleased to see that he continues the tradition of collaborating with leading epidemiologists worldwide to get the best possible result Jorn Olsen, Neil Pearce, and chitr Sitthi-Amorn Current, coming, and past presidents, International Epidemiological Association
To write a dictionary in any scientifi c discipline is a risky endeavor, because scientists often disagree. The nature of science is not to reach consensus but to advance our knowledge by bringing confl icting ideas to critical examinations. That is true also for how we defi ne the concepts we use. No dictionary will ever be able to satisfy all, nor should it try to. The aim of the International Epidemiological Association (IEA) in cosponsoring this dictionary in its more than 20 years’ history has been to facilitate communication among epidemiologists—to develop a “common language” to the extent that this is possible. We need a common language when we write papers, teach, and communicate fi ndings to the public. This “common language” changes over time, as anybody can see by reading the successive editions of this dictionary. The language changes because our understanding of the concepts changes over time and new research options bring forward new concepts. From the IEA, we want to thank John Last for his tremendous achievements as editor of the dictionary, and we are happy to welcome Miquel Porta as the new editor. Miquel has provided the smooth transition we were looking for, and we are pleased to see that he continues the tradition of collaborating with leading epidemiologists worldwide to get the best possible result. Jørn Olsen, Neil Pearce, and Chitr Sitthi-Amorn Current, coming, and past presidents, International Epidemiological Association www.ieaweb.org Foreword v
Foreword to the fourth edition 2001 IF I HAD TO LIMIT MY PROFESSIONAL BOOKCASE TO A SINGLE VOLUME. I WOULD choose this dictionary. With many new entries, updates, and other refinements in the fourth edition, the dictionary has grown from the original slim pocket book into a mature and substantial volume. John Last and his collaborators must be congratulated for their extraordinary devotion and productivity over the past 20 years, from which epidemiologists around the world have benefited. The dictionary's authority stems from its international recognition. It is an mmediate source for students and practitioners to verify their understanding of the increasing number of technical words in epidemiologic practice. It clarifies concepts that may not have been understood in class, fills many gaps in anyone's education, and jogs the memory of near-forgotten terms. It has no equal in the field of epidemiology The International Epidemiological Association is proud to have had such a ong-standing association with the dictionary. We all hope this relationship will continue indefinitely in the future, even though John Last, being mortal, will not He has set a high standard for his successors. We are grateful that he has prepared the way so well to ensure that the dictionary remains of contemporary relevance e coming decade Charles du v Florey International Epidemiological Association www.ieaweb.org
If I had to limit my professional bookcase to a single volume, I would choose this dictionary. With many new entries, updates, and other refi nements in the fourth edition, the dictionary has grown from the original slim pocket book into a mature and substantial volume. John Last and his collaborators must be congratulated for their extraordinary devotion and productivity over the past 20 years, from which epidemiologists around the world have benefi ted. The dictionary’s authority stems from its international recognition. It is an immediate source for students and practitioners to verify their understanding of the increasing number of technical words in epidemiologic practice. It clarifi es concepts that may not have been understood in class, fi lls many gaps in anyone’s education, and jogs the memory of near-forgotten terms. It has no equal in the fi eld of epidemiology. The International Epidemiological Association is proud to have had such a long-standing association with the dictionary. We all hope this relationship will continue indefi nitely in the future, even though John Last, being mortal, will not. He has set a high standard for his successors. We are grateful that he has prepared the way so well to ensure that the dictionary remains of contemporary relevance in the coming decades. Charles du V. Florey President, 1999–2002 International Epidemiological Association www.ieaweb.org Foreword to the Fourth Edition, 2001 vii