The Handbook of Research Synthesis and Meta-Analysis

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THE RUSSELL SAGE FOUNDATION The Russell Sage Foundation, one of the oldest of America’s general purpose foundations, was established in 1907 by Mrs. Margaret Olivia Sage for “the improvement of social and living conditions in the United States.” The Foundation seeks to fulfill this mandate by fostering the development and dissemination of knowledge about the country’s political, social, and economic problems . While the Foundation endeavors to assure the accuracy and objectivity of each book it publishes, the conclusions and interpretations in Russell Sage Foundation publications are those of the authors and not of the Foundation, its Trustees, or its staff. Publication by Russell Sage, therefore, does not imply Foundation endorsement. BOARD OF TRUSTEES Mary C. Waters, Chair Kenneth D. Brody Kathleen Hall Jamieson Nancy Rosenblum W. Bowman Cutter, III Melvin J. Konner Shelley E. Taylor Christopher Edley Jr. Alan B. Krueger Richard H. Thaler John A. Ferejohn Cora B. Marrett Eric Wanner Larry V. Hedges Library of Congress Cataloging-in-Publication Data The handbook of research synthesis and meta-analysis / Harris Cooper, Larry V. Hedges, Jeffrey C. Valentine, editors. — 2nd ed. p. cm. Rev. ed. of: The handbook of research synthesis. c1994. Includes bibliographical references and index. ISBN 978-0-87154-163-5 1. Research—Methodology—Handbooks, manuals, etc. 2. Information storage and retrieval systems—Research—Handbooks, manuals, etc. 3. Research—Statistical methods— Handbooks, manuals, etc. I. Cooper, Harris M. II. Hedges, Larry V. III. Valentine, Jeff C. IV. Handbook of research synthesis. Q180.55.M4H35 2009 001.4⬘2—dc22 2008046477 Copyright © 2009 by Russell Sage Foundation. All rights reserved. Printed in the United States of America. 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 written permission of the publisher. Reproduction by the United States Government in whole or in part is permitted for any purpose. The paper used in this publication meets the minimum requirements of American National Standard for Information Sciences—Permanence of Paper for Printed Library Materials. ANSI Z39.48-1992. RUSSELL SAGE FOUNDATION 112 East 64th Street, New York, New York 10065 10 9 8 7 6 5 4 3 2 1 To the authors of the Handbook chapters, for their remarkable cooperation and commitment to the advance of science and society ...