The R Manual for QCA has been updated to version 4.2 (September 2026). Among other changes, the manual now includes expanded sections on visualizing QCA results, with templates for creating, customizing, and combining X–Y plots and saving graphics as PDF or PNG files. There are also new sections on cluster analysis and robustness tests. The robustness tests follow the protocol developed by Oana and Schneider (2024), illustrated with replication data from a published study (Meissner and Mello 2022).

While the R Manual is written to get readers started, without assuming prior knowledge of R, it has grown into a 44-page document that provides step-by-step instructions for a complete QCA research cycle, from data management and calibration to necessary conditions, truth table analysis, solution types, and the visualization of results. All code is included in an accompanying R Script that can be adapted for one’s own purposes, complemented by two sample data sets. The analyses draw on the QCA package by Adrian Duşa and the SetMethods package by Ioana-Elena Oana and Carsten Q. Schneider, together with ggplot2 and further packages for visualization. For comprehensive treatments of QCA in R, see Duşa’s QCA with R (Springer, 2019) and Oana, Schneider, and Thomann’s Qualitative Comparative Analysis Using R (Cambridge University Press, 2021).

The R Manual for QCA (PDF file, R Script, and sample data) can be downloaded here and on Harvard Dataverse: https://doi.org/10.7910/DVN/KYF7VJ.

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During the week of August 17-21, I taught the course “Exploring Causal Complexity with Qualitative Comparative Analysis (QCA)” at the 30th Summer School in Social Sciences Methods of the Università della Svizzera italiana (USI) in Lugano, Switzerland. This has been the 8th time teaching this course in Lugano, ten years after its first edition in 2016. As in previous years, the intensive one-week course combined lectures with hands-on exercises in R, with dedicated time for participant presentations and individual consultations. The course follows my book Qualitative Comparative Analysis: An Introduction to Research Design and Application (Georgetown University Press, 2021) and the accompanying R Manual for QCA.

It is always a pleasure to see how participants apply QCA to research questions from across the social sciences. Thanks to the organizing team at USI for the smooth running of the summer school and to all participants for a constructive and very engaging week! And many thanks to Johannes Meuer (KLU Hamburg) for an inspiring guest lecture on calibration. We look forward to seeing that paper published!

If you are interested in taking part in 2027, please let me know (registration usually opens in December/January). For impressions from previous years of the USI Summer School, see here.

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On June 20, Hilde van Meegdenburg (Leiden University) and I presented our co-authored book manuscript “Uncovering Causal Symptoms: Case Study Research, Process Tracing, and Qualitative Comparative Analysis” at the Advances in Qualitative and Multi-Method Research (AQMMR) workshop, held virtually as part of the Institute for Qualitative and Multi-Method Research (IQMR) 2026 at Syracuse University. The manuscript was discussed by James Mahoney (Northwestern University) and Ingo Rohlfing (University of Passau). The workshop was organized by Diana Kapiszewski (Georgetown University) and Sebastian Karcher (Syracuse University), and coordinated with Alan Jacobs (University of British Columbia) and Erica Simmons (University of Wisconsin-Madison) as editors of the Methods for Social Inquiry series published by Cambridge University Press. Many thanks to our discussants and all participants for the constructive and intensive discussion of our manuscript—this has been tremendously helpful.

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On June 8, the article “Can the Public Sector Break the Mold? Exploring Antecedent Factors Driving Sensing Capabilities With fsQCA in the Tuscan Family and Community Nurse Model” was published in Public Policy and Administration (co-authored with Alessia Caputo, Lorenzo Taddeucci, and Milena Vainieri of the Sant’Anna School of Advanced Studies). In the article, we apply fuzzy-set QCA to explore conditions for developing organizational adaptability, using data from 26 Tuscan health districts. The online first version of the article can be accessed here.

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On June 2, I was invited to give a lecture on “Pacifism, Isolationism or Anti-Americanism? Explaining Public Opposition to Supporting Ukraine against Russia’s War of Aggression” (based on a paper co-authored with Wolfgang Wagner) at the Foreign Policy Lab of the Department of Political Science at the University of Innsbruck. The paper presents first results from a survey that was conducted under the NEST project (“Navigating the Storm: European Political Contestation in Geopolitical Transformation”), where I am involved as Co-Investigator, together with my VU colleagues Chendi Wang (PI), Ben Crum, and Wolfgang Wagner. Thanks for the kind invitation and organization of the event to Martin Senn, Anna Saischek, and Katja Astner, and thanks to all participants for their helpful comments and questions!

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On April 2, I was invited to give an online methods masterclass for the members of the Evaluation and Statistics cadres of the Foreign, Commonwealth & Development Office of the United Kingdom, speaking about “Qualitative Comparative Analysis (QCA) for Foreign Policy Analysis”. The talk comprised a concise introduction to the method and approach of QCA, based on my 2021 book with Georgetown University Press. For the second part, the FCDO members asked me to speak about my applied QCA study on the Unintended Consequences of UN Sanctions, an open-access article that was co-authored with Katharina Meissner (replication data for this article is available here: https://doi.org/10.7910/DVN/9BGOYQ). Many thanks to Harry Achillini for the invitation and organization–and to all participants for the intriguing questions during the Q&A!

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On March 18–20, I attended the 5th Annual QCA Conference of the Americas (AQCA 2026), held at the Carl H. Lindner College of Business at the University of Cincinnati. I was invited to give the keynote speech, where I talked about “Uncovering Causal Symptoms: QCA in Multi-Method Research,” based on a book manuscript co-authored with Hilde van Meegdenburg (Leiden University). The talk explored how QCA can be combined with case study research and process tracing as part of a multi-method research strategy—an issue that is becoming increasingly relevant as configurational approaches continue to expand across disciplines.

AQCA brings together a broad, cross-disciplinary community of QCA empirical researchers and methodologists, offering opportunities to present and receive feedback on current research, share methodological developments, and discuss new directions in configurational-comparative research. A hallmark of the conference is its inclusive character, welcoming contributions not only from QCA’s traditional strongholds in sociology, political science, and management but also from fields such as education, environmental studies, health policy, and information systems.

Thanks to the AQCA 2026 Organizing Committee–Joanna Campbell (University of Cincinnati, local organizer), Claude Rubinson (University of Houston-Downtown), Gary Goertz (University of Notre Dame), and Peer Fiss (University of Southern California)—for putting together an engaging program and for inviting me to Cincinnati. And thanks to all participants who made this a fantastic event!

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The recently published book The Changing Fights and Fighters of Contemporary War, edited by Marie Robin (Leiden University), Amelie Theussen (Royal Danish Defense College), and Kerstin Bree Carlson (Roskilde University), includes my chapter “Explaining European Military Engagement in the Fight Against Daesh”. A first draft of this chapter was presented in 2020 at the annual conference of the Center for War Studies (CWS) conference of the University of Southern Denmark. Many thanks to Marie Robin, Amelie Theussen, and Kerstin Bree Carlson for shepherding this book project to publication, despite numerous obstacles along the way! Thanks also for the constructive comments and suggestions on my chapter, also to the other participants and discussants at the CWS conference.

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The Perelman School of Medicine at the University of Pennsylvania has acquired funding from the National Institutes of Health (NIH) for a four-year research project, led by Meeta Prasad Kerlin (PI), to better understand the complex interplay between contextual and intervention features in care delivery for patients that undergo invasive mechanical ventilation (total budget: USD 2,816,250; budget in 2026: USD 688,364; project number 5R01HL180743). The project involves nine researchers across five domains. I am serving as methodological consultant on the QCA component of the multi-method research design.

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The program for the 30th Summer School in Social Sciences Methods at the Università della Svizzera italiana in Lugano, Switzerland has been announced: I’m offering Exploring Causal Complexity with Qualitative Comparative Analysis (QCA) during the week of August 17-21, 2026. For impressions from previous years, see here. This course provides a complete introduction to QCA, including R software packages (see detailed course description below). For more information, also on registration, please see the USI Summer School Website. If you have any questions about the course, please don’t hesitate to contact me.

From the course description: Causal complexity is everywhere in the social sciences—yet most researchers lack the systematic tools to capture it rigorously. In this intensive 5-day workshop (28 contact hours) you will learn how to design, apply, and publish empirical research with Qualitative Comparative Analysis (QCA) in the R software environment. The course follows the comprehensive framework developed in Mello (2021, Georgetown University Press), progressing systematically from the foundations of QCA to advanced applications.

The course emphasizes research design alongside analytical techniques, addressing both conceptual foundations and practical application of QCA. You will follow an ideal-typical research process, starting with empirical illustrations of where and how QCA is used in the social sciences. Foundational sessions explore key principles, such as set theory, Boolean algebra, and the calibration of crisp and fuzzy sets, while guiding you through the analytical protocol for identifying patterns of causal complexity using truth tables and Boolean minimization.

The course progresses step by step, from study design to the interpretation of results, incorporating hands-on exercises with examples from published studies and R script templates to adapt for your own purposes. Advanced topics—including multi-method research, robustness tests, and recent developments in QCA—will be tailored to your needs and research interests. Opportunities to present your individual project and explore potential applications further enhance the workshop.

Designed to be inclusive, the workshop welcomes participants at all levels—from PhD students to senior researchers—and strikes a balance between theory, practical exercises, and individualized support. A strong emphasis on collaboration and dialogue in a small group setting ensures ample time for consultation, group discussions, and networking. By the end of the workshop, you will be equipped with the theoretical knowledge and practical skills needed to apply QCA effectively, providing a robust framework for addressing causal complexity in comparative social science research.

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