Gary Goertz & James Mahoney
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Gary Goertz & James Mahoney A Tale of Two Cultures Qualitative and Quantitative Research in the Social Sciences Gary Goertz and James Mahoney PRINCETON UNIVERSITY PRESS PRINCETON AND OXFORD Copyright © 2012 by Princeton University Press Published by Princeton University Press, 41 William Street, Princeton, New Jersey 08540 In the United Kingdom: Princeton University Press, 6 Oxford Street, Woodstock, Oxfordshire OX20 ITW press.princeton.edu All Rights Reserved Library of Congress Cataloging-in-Publication Data Goertz, Gary, 1953- A tale of two cultures : qualitative and quantitative research in the social sciences I Gary Goertz and James Mahoney. p. em. Includes bibliographical references and index. ISBN 978-0-691-14970-7 (hardcover : alk. paper) -ISBN 978-0-691-14971-4 (pbk.: alk. paper) I. Political science-Research-Methodology. 2. Political sociology-Research-Methodology. 3. Social sciences-Research-Methodology. I. Mahoney, James, 1968- II. Title. JA86.G56 2012 30 I .072----<lc23 2012010983 British Library Cataloging-in-Publication Data is available This book has been composed in Times and Helvetica Printed on acid-free paper. oo Typeset by S R Nova Pvt Ltd, Bangalore, India Printed in the United States of America 10 9 8 7 6 5 4 3 2 I Contents Preface Vll 1. Introduction 2. Mathematical Prelude: A Selective Introduction to Logic and Set Theory for Social Scientists 16 I. CAUSAL MODELS AND INFERENCE 3. Causes-of-Effects versus Effects-of-Causes 41 4. Causal Models 51 5. Asymmetry 64 6. Hume's Two Definitions of Cause 75 II. WITHIN-CASE ANALYSIS 7. Within-Case versus Cross-Case Causal Analysis 87 8. Causal Mechanisms and Process Tracing 100 9. Counterfactuals 115 Ill. CONCEPTS AND MEASUREMENT 10. Concepts: Definitions, Indicators, and Error 127 11. Meaning and Measurement 139 12. Semantics, Statistics, and Data Transformations 150 13. Conceptual Opposites and Typologies 161 vi Contents IV. RESEARCH DESIGN AND GENERALIZATION 14. Case Selection and Hypothesis Testing 177 15. Generalizations 192 16. Scope 205 17. Conclusion 220 Appendix 227 Name Index 231 Subject Index 235 Preface This book analyzes quantitative and qualitative research in the social sci ences as separate cultures. We arrived at this "two cultures" view in the course of carrying out teaching and research over the last decade. We repeat edly discovered ways in which qualitative and quantitative researchers vary in their methodological orientations and research practices. We also observed misunderstandings and constrained communication among qualitative and quantitative researchers. As we tried to make sense of these facts, it became clear to us that the qualitative and quantitative traditions exhibit all the traits of separate cultures, including different norms, practices, and tool kits. Our goal in writing this book is to increase scholarly understanding of the ways in which these cultures are different as well as the rationales behind those differences. In order to do this, we cover a large range of methodological topics. These topics concern key research design and data analysis questions that nearly all social scientists must face. Many of the topics covered here are not addressed in research methods textbooks and cannot be found together in any convenient book on methodology, qualitative or quantitative. Hence, one way to read and use this volume is as a guide to the range of questions that any social scientist might consider when designing and carrying out research. We first learned about each other's research while teaching at the Institute for Qualitative and Multi-Method Research, and we would like to express our gratitude to the many students who attended this Institute and gave us feedback on our two cultures argument over the years. We owe the Institute's leader, Colin Elman, special thanks for making room for our work in the annual program. We are also grateful to the Organized Section on Qualitative and Multi-Method Research of the American Political Science Association, which provided newsletter and conference outlets for early drafts of several chapters. vii viii Preface The first version of our argument was an article published in Political Analysis in 2006. We are grateful to Robert S. Erikson, who was editor of Political Analysis, for going forward with that early piece. Without its publication, we might not have been inspired to continue to find and explore differences in quantitative and qualitative research. We discussed parts of this manuscript while teaching graduate courses on methodology at the University of Arizona and Northwestern University. It was in interacting with our graduate students--quantitative and qualitative that many of the topics rose to the top of our list of important methodological issues. In addition, much of this material has been presented in work shops and short courses in the United States, Europe, and Latin America. We express our thanks to the graduate students in all of these courses, workshops, and short courses for their insights. We especially acknowledge the contribution of Khairunnisa Mohamedali and Christoph Nguyen, who carried out the survey of articles reported in the appendix. We also thank the professors and students who offered comments on presentations of this material at Northwestern University, the University of Wisconsin, and Yale University. At Princeton University Press, Chuck Myers helped to secure reviewer reports from which we benefited. Chuck also worked to speed the produc tion process along. We are grateful to Glenda Krupa for copyediting the manuscript. We acknowledge Sage Publications Inc. for granting permission to publish the epigraph at the beginning of Chapter 13, which originally appeared in Applied Regression Analysis and Generalized Linear Models (Second Edition) by John Fox (Los Angeles, CA: Sage Publications, 2008). Finally, we received insightful comments from a number of col leagues: Michael Baumgartner, Nathaniel Beck, Andrew Bennett, Janet Box-Steffensmeier, Bear Braumoeller, David Collier, Thad Dunning, Colin Elman, John Gerring, Jack Levy, Diana Kapiszewski, Charles C. Ragin, Carsten Schneider, Jason Seawright, David Waldner, and Sebastian Zaja. We know that not all of these colleagues agree with everything that we say in this book. But we hope that engaging and debating the ideas presented here will itself help to move forward both quantitative and qualitative research in the social sciences. A Tale of Two Cultures Chapter 1 Introduction In this book, we explore the relationship between the quantitative and qualitative research traditions in the social sciences, with particular emphasis on political science and sociology. We do so by identifying various ways in which the traditions differ. They contrast across numerous areas of method ology, ranging from type of research question, to mode of data analysis, to method of inference. We suggest that these differences are systematically and coherently related to one another such that it is meaningful to speak of distinct quantitative and qualitative research paradigms. We treat the quantitative and qualitative traditions as alternative cul tures. Each has its own values, beliefs, and norms. Each is associated with distinctive research procedures and practices. Communication within a given culture tends to be fluid and productive. Communication across cultures, however, tends to be difficult and marked by misunderstanding. When scholars from one tradition offer their insights to members of the other tradition, the advice is often viewed as unhelpful and inappropriate. The dissonance between the alternative cultures is seen with the miscom munication, skepticism, and frustration that sometimes mark encounters between quantitative and qualitative researchers. At its core, we suggest, the quantitative-qualitative disputation in the social sciences is really a clash of cultures. Like all cultures, the quantitative and qualitative ones are not mono lithic blocks (see Sewell (2005) for a good discussion of the concept of "culture"). They are loosely integrated traditions, and they contain internal contradictions and contestation. The particular orientations and practices that compose these cultures have changed over time, and they continue to evolve today. The two cultures are not hermetically sealed from one another 2 Chapter 1 but rather are permeable and permit boundary crossing. Nevertheless, they are relatively coherent systems of meaning and practice. They feature many readily identifiable values, beliefs, norms, and procedures. By emphasizing differences between qualitative and quantitative re search, this book stands in contrast to King, Keohane, and Verba's work, Designing Social Inquiry: Scientific Inference in Qualitative Research. They famously argue that "the differences between the quantitative and qualitative traditions are only stylistic and are methodologically and substantively unimportant" (1994, 4). They believe that the two traditions share a single logic of inference, one that can be largely summarized in terms of the norms of statistical analysis. The differences between the two traditions that they identify concern surface traits, especially the use of numbers versus words. We reject the assumption that a single logic of inference founded on statistical norms guides both quantitative and qualitative research. Nor do we believe that the quantitative-qualitative distinction revolves around the use of numbers versus words. Instead, we see differences in basic orientations to research, such as