Qualitative Comparative Analysis

An Introduction to Research Design and Application

Patrick A. Mello

A comprehensive and accessible guide to learning and successfully applying QCA
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A comprehensive and accessible guide to learning and successfully applying QCA

Social phenomena can rarely be attributed to single causes—instead, they typically stem from a myriad of interwoven factors that are often difficult to untangle. Drawing on set theory and the language of necessary and sufficient conditions, qualitative comparative analysis (QCA) is ideally suited to capturing this causal complexity. A case-based research method, QCA regards cases as combinations of conditions and compares the conditions of each case in a structured way to identify the necessary and sufficient conditions for an outcome.

Qualitative Comparative Analysis: An Introduction to Research Design and Application is a comprehensive guide to QCA. As QCA becomes increasingly popular across the social sciences, this textbook teaches students, scholars, and self-learners the fundamentals of the method, research design, interpretation of results, and how to communicate findings.

Following an ideal typical research cycle, the book’s ten chapters cover the methodological basis and analytical routine of QCA, as well as matters of research design, causation and causal complexity, QCA variants, and the method’s reception in the social sciences. A comprehensive glossary helps to clarify the meaning of frequently used terms. The book is complemented by an accessible online R manual to help new users to practice QCA’s analytical steps on sample data and then implement with their own findings. This hands-on textbook is an essential resource for students and researchers looking for a complete and up-to-date introduction to QCA.

Table of Contents

List of Boxes, Figures, and Tables



1. Introduction

What Is Qualitative Comparative Analysis?

How To Use This Book

The QCA Research Cycle

A Brief History of QCA

Trends in QCA Applications

Book Outline


2. Research Design

Research Questions

Uses of QCA

Case Selection

Condition Selection

Multi-Method Research Designs

A Survey of Empirical Applications


3. Set Theory

Crisp and Fuzzy Sets

Set Operations

Truth Tables

Necessary and Sufficient Conditions

Assessing Set Relations


4. Causation and Causal Complexity

Theories of Causation in the Social Sciences

Causal Complexity

Causal Analysis


5. Calibrating Sets

Measurement and Calibration

Calibration Procedures

Types of Data

The Direct Method of Calibration

Calibration: Applied Examples

Common Misconceptions about Calibration

Good Practices of Calibration


6. Measures of Fit

Set-Theoretic Consistency

Set-Theoretic Coverage

Proportional Reduction in Inconsistency

Relevance of Necessity


7. Set-Theoretic Analysis

Analyzing Necessary Conditions

Truth Table Construction

Truth Table Analysis

Solution Terms

Counterfactual Analysis


8. QCA Variants

Multi-Value QCA

Temporal QCA

Two-Step QCA

Fuzzy Set Ideal Type Analysis

Related Methods and Approaches


9. QCA and Its Critics

Analytical Robustness

Comparisons with Other Methods

Formalization and Algorithms

Causal Analysis and Solution Terms

Recognizing QCA’s Strengths and Limitations


10. Conclusion

Good Research Practice

Documenting and Communicating QCA Results

QCA Resources

The Way Ahead


Appendix: Link to Online R Manual




About the Author


"A well-written, lucid textbook dealing with all the essentials that one needs to do a QCA analysis. Just the right amount of technical details to get the basic ideas across but easily understandable to those interested in learning QCA or brushing up on recent developments. A user-friendly R manual accompanies the book, allowing one to quickly start doing analyses."—Gary Goertz, professor of political science, University of Notre Dame

"Deftly navigating decades of methodological advancement, discussion, and debate, Mello produces a clearly written and well-reasoned guide to understanding QCA and how to conduct it effectively. Researchers from all disciplines will be well served by Qualitative Comparative Analysis: An Introduction to Research Design and Application, which teaches those new to the method how to do it well and provides a comprehensive reference for experienced QCA researchers."—Claude Rubinson, associate professor of sociology, University of Houston-Downtown

"Patrick Mello offers a thorough but approachable introduction to Qualitative Comparative Analysis (QCA). He grounds his presentation of the approach in a discussion of the QCA research cycle, offering important analytic insights for novices and experts alike. Mello also includes 'behind-the-scaffolding' infoboxes where authors of published QCA studies comment on their analytic strategies."—Charles C. Ragin, Chancellor's Professor of Sociology at the University of California, Irvine

"A diverse set of empirical illustrations, a clear presentation of QCA as a research approach, and a sharp but yet accessible hands-on presentation of QCA protocols from A to Z: this textbook is a great companion for anyone seriously engaging with QCA."—Benoît Rihoux, University of Louvain and COMPASSS international network

"Mello’s book especially stands out from other publications on QCA in three different areas: the chapters on research design (Chapter II), QCA and its critics (Chapter IX) and the online ‘R Manual’ that accompanies the publication. These elements are especially interesting given the fact they are not discussed in many texts on QCA, thus filling an additional gap in the literature on the method."—Political Studies Review


Supplemental Materials


About the Author

Patrick A. Mello is a visiting scholar at the Willy Brandt School of Public Policy at the University of Erfurt and privatdozent at the TUM School of Governance of the Technical University of Munich. He is the author of Democratic Participation in Armed Conflict: Military Involvement in Kosovo, Afghanistan, and Iraq, winner of the 2015 Dissertation Award from the German Political Science Association. His articles have appeared in journals such as Foreign Policy Analysis, European Journal of International Security, and the British Journal of Politics and International Relations.

240 pp., 7 x 10
32 figures, 46 tables
ISBN: 978-1-64712-144-0
Dec 2021

240 pp., 7 x 10
32 figures, 46 tables
ISBN: 978-1-64712-145-7
Dec 2021

240 pp.
32 figures, 46 tables
ISBN: 978-1-64712-146-4
Dec 2021

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