Cooper - Research synthesis and meta-analysis: a step-by-step approach

Fifth Edition

To Elizabeth

Research Synthesis and Meta-Analysis

A Step-by-Step Approach

Fifth Edition

APPLIED SOCIAL RESEARCH METHODS SERIES

• Harris Coope
• Duke University

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Library of Congress Cataloging-in-Publication Data

Cooper, Harris M.

Research synthesis and meta-analysis / Harris Cooper, Duke University. Fifth Edition.

pages cm

Revised edition of the authors Research synthesis and meta-analysis, 2010.

Includes bibliographical references and indexes.

ISBN 978-1-4833-3115-7 (pbk. : alk. paper)

1. Social sciencesResearch. I. Title.

[DNLM: 1. Meta-Analysis as Topic. 2. Research Design.]

H62.C5859 2016

300.72dc232015029254

This book is printed on acid-free paper.

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Every scientific investigation begins with the researcher examining reports of previous studies related to the topic of interest. Without this step, researchers cannot expect their efforts to contribute to an integrated, comprehensive picture of the world. They cannot achieve the progress that comes from building on the efforts of others. Also, investigators working in isolation are doomed to repeat the mistakes made by their predecessors.

Similar to primary data collection, researchers need guidance about how to conduct a research synthesishow to find research already conducted on a particular topic, gather information from research reports, evaluate the quality of research, integrate results, interpret the cumulative findings, and present a comprehensive and coherent report of the synthesis findings. This book presents the basic steps in carrying out a research synthesis. It is intended for use by social and behavioral scientists who are unfamiliar with research synthesis and meta-analysis but who possess an introductory background in basic research methods and statistics.

Instead of a subjective, narrative approach to research synthesis, this book presents an objective, systematic approach. Herein, you will learn how to carry out an integration of research according to the principles of good science. The intended result is a research synthesis that can be replicated by others, can create consensus among scholars, and can lead to constructive debate on unresolved issues. Equally important, users of this approach should complete their research synthesis feeling knowledgeable and confident that their future primary research can make a contribution to the field.

The scientific approach to research synthesis has rapidly gained acceptance. In the years between its first and fifth editions, the procedures outlined in this book have changed from being controversial practices to being accepted ones. Indeed, in many fields the approach outlined herein is now obligatory. The years have also brought improvements in synthesis techniques. The technology surrounding literature searching has changed dramatically. The statistical underpinnings of meta-analysisthe quantitative combination of study resultshave been developed and the application of these procedures has become widely accessible. Many techniques have been devised to help research synthesists present their results in a fashion that will be meaningful to their audience. Methodologists have proposed ways to make syntheses more resistant to criticism.

This fifth edition incorporates these changes. Most notably, . They include new statistics for describing meta-analytic results and new techniques for combining complex data structures. The latter are touched on only briefly because they require more-advanced statistical training, unlike the other techniques I cover. Also, the references have been updated globally through the text.

Several institutions and individuals have been instrumental in the preparation of the different editions of this book. First, the United States Department of Education provided research support while the first and third editions of the manuscript were prepared, and the W. T. Grant Foundation while the fifth edition was prepared. Special thanks go to numerous former and current graduate students: Kathryn Anderson, Brad Bushman, Vicki Conn, Amy Dent, Maureen Findley, Pamela Hazelrigg, Ken Ottenbacher, Erika Patall, Georgianne Robinson, Patrick Smith, David Tom, and Julie Yu. Each performed a research review in his or her area of interest under my supervision. Each has had his or her work serve as an example in at least one edition of the book, and four of their efforts are used in the current edition to illustrate the different synthesis techniques. Jeff Valentine, also a former student of . Four reference librarians, Kathleen Connors, Jolene Ezell, Jeanmarie Fraser, and Judy Pallardy, helped with the chapter on literature searching. Larry Hedges and Terri Pigott have examined my exposition of statistical techniques. Three more graduate students, Ashley Bates Allen, Cyndi Kernahan, and Laura Muhlenbruck, read and reacted to chapters in various editions. Angela Clinton, Cathy Luebbering, and Pat Shanks typed, and retyped, and proofread my manuscripts. My sincerest thanks to these friends and colleagues.

Harris Cooper

Durham, North Carolina

The author and SAGE Publications would like to thank the following reviewers:

Andrea E. Berndt, The University of Texas Health Science Center at San Antonio,

Stefan G. Hofmann, Boston University

Jack W. Meek, University of La Verne

Laura J. Meyer, University of Denver