Swiss Summer School 2016

Patrick A. Mello
Qualitative Comparative Analysis (QCA)

Patrick A. Mello is a Research Associate and Lecturer at Technische Universität of Munich. His substantive research focuses on matters of international relations theory, international security, and foreign policy analysis. His methodological research interest lies in comparative methods, with an emphasis on fuzzy-set Qualitative Comparative Analysis. His book Democratic Participation in Armed Conflict: Military Involvement in Kosovo, Afghanistan, and Iraq has been published with Palgrave Macmillan in 2014. The book received the Best Dissertation Award 2015 of the German Political Science Association. Mello's work has appeared in journals such as the European Journal of International Relations and the Journal of International Relations and Development. [Patrick A. Mello's website]

Workshop contents and objectives

The workshop provides participants with a thorough introduction to Qualitative Comparative Analysis (QCA), both as a research approach and as a data analysis technique. In recent years, this set-theoretic method has gained recognition among social scientists as a methodological approach that holds specific benefits for comparative studies. The course begins by familiarizing participants with the foundations of set theory and the basic concepts of the methodological approach of QCA, including necessary and sufficient conditions, Boolean algebra, and fuzzy logic. The next step is devoted to the calibration of empirical data into crisp and fuzzy sets. Once these essentials are in place, the course moves on to the construction and analysis of truth tables as the core of the QCA procedure. Here, we will also spend time to discuss typical challenges that arise during a truth table analysis and techniques to overcome such problems. Finally, the course will introduce consistency and coverage as parameters of fit as well as additional measures to assess the robustness of QCA results.

Besides the technical introduction of QCA and its variants, the course will provide opportunities to discuss general aspects of comparative research projects, including criteria for concept building and case selection, data-related issues, and the incorporation of causally relevant notions of time into the analytical procedure.

Throughout the course, participants will conduct set-theoretic analyses within the R software environment (packages "QCA" and "SetMethods"). The software will be introduced on the first day and used for exercises and examples throughout the course, so that participants gain a level of proficiency that enables them to conduct their own QCA analyses upon the completion of the course. Participants are encouraged to bring their own qualitative and/or quantitative data for course exercises (if available, preliminary data is fine). In addition, datasets from published studies will be made available and used for in-course exercises.


Course participants are not required to have any previous knowledge of QCA or the R software environment and its relevant packages. Nonetheless, an advance reading of the recommended literature is advised. To start working with the software from day 1, a prior introduction to the basic functions of R and RStudio will be beneficial.


  1. Mello, Patrick A. (2014) Democratic Participation in Armed Conflict. Military Involvement in Kosovo, Afghanistan, and Iraq. Basingstoke: Palgrave Macmillan.
  2. Ragin, Charles C. (2008) Redesigning Social Inquiry: Fuzzy Sets and Beyond. Chicago: University of Chicago Press.
  3. Rihoux, Benoît and Charles C. Ragin, eds. (2009) Configurational Comparative Methods. Qualitative Comparative Analysis (QCA) and Related Techniques. Thousand Oaks and London: Sage.
  4. Schneider, Carsten Q. and Claudius Wagemann (2012) Set-Theoretic Methods for the Social Sciences: A Guide to Qualitative Comparative Analysis. Cambridge: Cambridge University Press.