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  • Dec 2017: Paper accepted at SVPW's annual conference, 5 - 6 Feb 2018, University of Geneva

    The Swiss Political Science Association will hold its annual conference at the University of Geneva from 5-6 February 2018. I will present a paper titled "Small Act, Huge Effect: Algorithmic Sources of Publication Bias in Political Science Research" (co-authored with Tim Haesebrouck from the University of Ghent) in the Empirical Methods section. In this paper, we demonstrate how the uncritical import of the Quine-McCluskey algorithm from electrical engineering into research with Qualitative Comparative Analysis (QCA) in the 1980s has led to considerable publication bias over three decades of research with QCA. Updates on this paper project can be retrieved from my ResearchGate website.

  • Dec 2017: Paper accepted at PSA's Political Methodology conference, 12 Jan 2018, University of Essex

    The Political Methodology section of the UK's Political Studies Association will hold its third annual conference at the University of Essex on the 12th of January 2018. I will present a paper titled "Small Act, Huge Effect: Algorithmic Sources of Publication Bias in Political Science Research" (co-authored with Tim Haesebrouck from the University of Ghent). In this paper, we demonstrate how the uncritical import of the Quine-McCluskey algorithm from electrical engineering into research with Qualitative Comparative Analysis in the 1980s has led to considerable publication bias. Updates on this paper project can be retrieved from my ResearchGate website.

  • Oct 2017: Article on model ambiguities in QCA published in Sociological Methods & Research 46(4)

    For many years, social scientists have relied on Qualitative Comparative Analysis (QCA) for the purpose of configurational causal modeling. However, we reveal that a severe problem in the application of QCA has gone unnoticed so far: model ambiguities. Mainly due to the uncritical import of an algorithm that is unsuitable for causal modeling, researchers have so far been unaware of this problem. In consequence, there exists an indeterminable risk for practically all QCA studies published in the last quarter-century to have presented findings that their data did not warrant. We identify the source of ambiguities and examine to what extent they affect empirical research. For more details, visit the article's website.

  • Sep 2017: QCA tutorial published in American Journal of Evaluation 38(3)

    Configurational research has long been one of the main preoccupations of evaluation scholars and practitioners. In this article, I provide a hands-on tutorial for Qualitative Comparative Analysis (QCA)-currently the most popular configurational comparative method. In drawing on a recent evaluation of patient follow-through effectiveness in Lynch syndrome tumor-screening programs, I explain the search target of QCA, introduce its core concepts, guide readers through the procedural protocol of this method and alert them to mistakes frequently made in QCA's use. An annotated replication file for the QCApro package accompanies this tutorial. For more details, visit the article's website.

  • Aug 2017: Paper accepted at SCIQUAL conference, 13 - 14 Sep 2017, Utrecht University

    The SCIQUAL (scientific integrity in qualitative research) conference focuses on different aspects of scientific integrity pertaining to qualitative research methods. Tim Haesebrouck and I present a paper titled "Small Act, Huge Effect: Algorithmic Sources of Publication Bias in Political Science Research". In this paper, we reveal an unnoticed source of publication bias in political science research that has employed the method of Qualitative Comparative Analysis (QCA). By drawing on data from almost 160 QCA studies, we show that the uncritical import of the Quine-McCluskey algorithm from electrical engineering to the social sciences has led to overly unambiguous research findings.

  • May 2017: 5-Day Workshop Seminar at Regenstrief Institute, Indianapolis, USA, 25-29 September 2017

    From 25-29 September 2017, Michael Baumgartner and I offer an intensive 5-day introduction to Qualitative Comparative Analysis (QCA) and Coincidence Analysis (CNA) at the Regenstrief Institute - an internationally recognized healthcare research organization affiliated with Indiana University's School of Medicine. Participants will be guided through the nuts and bolts of configurational data analysis as well as cutting-edge methodological innovations. Moreover, we demonstrate how to make the most of current software for QCA and CNA. Individual consultation sessions will be offered to help participants with the methodological aspects of their research projects. Course and registration details can be found here.

  • May 2017: Article on military burden sharing published advance online at Defence and Peace Economics

    Military burden sharing has been a subject of repeated debates. In this connection, the fact that some European Union (EU) member states have carried disproportionate shares of the burden of Common Security and Defence Policy (CSDP) operations is a puzzle that remains unaccounted for. We address this gap by analyzing determinants of contribution levels to CSDP operations. Employing a multi-method design that combines insights from collection action theory with those from integrated theories of burden sharing, we find that EU countries contribute in positive disproportion with their capabilities when they have a strong peacekeeping tradition and elections are distant. For more details, visit the article's website.

  • May 2017: Methodological evaluation of QCA published advance online at Sociological Methods & Research

    To date, hundreds of researchers have employed the method of Qualitative Comparative Analysis (QCA) for the purpose of causal inference. In a series of simulation studies, several authors have recently questioned the correctness of QCA in this connection. These previous attempts at evaluating QCA, however, have been defective. We lay out a set of formal criteria for an adequate evaluation before implementing a battery of inverse-search trials to test how QCA performs in different recovery contexts. Our results indicate that QCA is correct when generating the parsimonious solution type, but incorrect in conjunction with the conservative and the intermediate solution type. For more details, visit the article's website.

  • Apr 2017: Presentation at 13th ESA General Conference, 29 Aug - 1 Sep 2017, Athens, Greece

    My paper proposal titled "Limited empirical diversity and the incorrectness of Qualitative Comparative Analysis" has been accepted for presentation at the 13th General Conference of the European Sociological Association, to be held 29 Aug - 1 Sep 2017 in Athens, Greece. I show in this paper that two of QCA's three search strategies supplement empirical data with matching artificial data when there is limited empirical diversity. Frequently, however, these artificial data violate the causal structure QCA seeks to uncover, whereby causal fallacies are induced.

  • Mar 2017: Presentation at DVPW's Empirical Methods section conference, 12-13 May 2017, Mainz, Germany

    My paper proposal titled "Limited empirical diversity and the incorrectness of Qualitative Comparative Analysis" has been accepted for presentation at the Annual Conference of the Empirical Methods section of the German Political Science Association (DVPW), to be held 12-13 May 2017 in Mainz, Germany. I show in this paper that two of QCA's three search strategies supplement empirical data with matching artificial data when there is limited empirical diversity. Oftentimes, however, these artificial data violate the causal structure QCA seeks to uncover, whereby causal fallacies are induced.

  • Mar 2017: Award of Swiss National Science Foundation Professorship

    For a project titled "ACCORds: Advancing Configurational Comparative Research Methods", I have been awarded a Swiss National Science Foundation Professorship, funded with 1.4 million Swiss Francs, at the University of Lucerne. With this project, I intend to take Configurational Comparative Methods (CCMs), such as Qualitative Comparative Analysis and Coincidence Analysis, a quantum leap forward. The project aims to enhance the functionality of CCMs, to address epistemological questions, and to develop software that makes ACCORds' advances available to the scientific community.

  • Feb 2017: Paper proposal accepted for 7th General Conference of EPSA, 22-24 June 2017, Milan, Italy

    My paper proposal titled "A Phantom Menace: Random Data, Model Specification and Causal Inference in Qualitative Comparative Analysis" has been accepted for presentation at the 7th Annual General Conference of the European Political Science Association (EPSA), to be held 22-24 June 2017 in Milan, Italy. I demonstrate in this paper that benchmarks for preventing QCA from drawing incorrect inferences, which have often been invoked as a standard of good practice for model specification in applied research, are not merely ill-conceived but they even induce QCA to commit causal fallacies.

  • Feb 2017: Cyber Seminar at U.S. Department of Veterans Affairs

    Together with Michael Baumgartner from the University of Geneva, I will give a 1-hour cyber seminar titled "Configurational Data Analysis with QCA and CNA for Health Researchers" at the U.S. Department of Veterans Affairs (VA) on 2 March. VA operates one of the largest integrated health care system in the world, with more than 1,700 hospitals, clinics, community living centers, domiciliaries, readjustment counseling centers, and other facilities. Public health is one of the fastest growing areas with respect to the use of configurational methods. If you would like to attend, simply follow this link.

  • Dec 2016: Presentation at PSA's Political Methodology Conference, University of Oxford

    The Political Methodology section of the UK's Political Studies Association will hold its second annual conference at the University of Oxford on the 13th of January 2017. I will present a paper titled "Often trusted but never (properly) tested: Evaluating Qualitative Comparative Analysis", which is co-authored with Michael Baumgartner from the University of Geneva. Conference details and the full programme can be found here. A previous conference version of our paper to be presented and corresponding presentation slides from the recent 4th QCA Expert Workshop (7-8 December 2016, University of Zurich, Switzerland) can be retrieved from my ResearchGate website.

  • Oct 2016: Article on standards of good practice in QCA published in Political Analysis 24(4)

    The introduction of Qualitative Comparative Analysis (QCA) has revolutionized research on necessary conditions. Standards of good practice for QCA have long demanded that the results of tests for necessity constrain QCA's minimization process so as to enhance the quality of parsimonious and intermediate solutions. Schneider and Wagemann's Theory-Guided/Enhanced Standard Analysis (T/ESA) is currently being adopted as the new state-of-the-art in this respect. However, I demonstrate that, once bias in necessity tests is accounted for, T/ESA will produce conservative solutions, and not enhanced parsimonious or intermediate ones. For more details, visit the article's website.

  • Sep 2016: Comment on QCA evaluation published in Sociological Methodology 46(1)

    In Sociological Methodology 44(1), Lucas and Szatrowski (2014; abbr. LS) argue that Qualitative Comparative Analysis (QCA) suffers from an in-built confirmation bias, and therefore urge that QCA be abandoned. With this comment, we pursue four related objectives: (1) we explain why correlation-based evaluation designs as used by LS for testing QCA's power of discrimination with respect to causally irrelevant factors are unsuitable; (2) we show how appropriate tests must be constructed; (3) we offer an R function that implements a routine for such tests; (4), we conduct three series of tests, all of whose results indicate that QCA does not suffer from confirmation bias. For more details, visit the article's website.

  • Apr 2016: Reply to Munck, Paine and Schneider published in Comparative Political Studies 49(6)

    In this symposium reply to Gerardo Munck, Jack Paine, and Carsten Schneider, we focus on two related problems that unite these authors' pieces, that are of high relevance beyond the current debate, and that we have addressed only indirectly in our original article "Still Lost in Translation! A Correction of Three Misunderstandings Between Configurational Comparativists and Regressional Analysts". The first problem concerns the over-inflation of the Boolean concept of necessity in QCA, the second one ignorance about the formalities of the theory of causation which QCA rests on. For more details, visit the article's website.

  • Apr 2016: Article on methods debate published in Comparative Political Studies 49(6)

    Even after two decades, representatives of configurational comparative methods (CCMs) and those of regressional analytic methods (RAMs) continue talking at cross purposes. In this article, we clear up three misunderstandings: a) CCMs and RAMs use the same logic of inference, b) the same hypotheses can be associated with one or the other set of methods, c) multiplicative RAM interactions and CCM conjunctions are based on the same concept of causal complexity. Our objective is to contribute to a more informed debate than has been the case so far. For more details, visit the article's website.

  • Jan 2016: New R package for performing and evaluating Qualitative Comparative Analysis

    With numerous fixes and improvements on its predecessor package QCA, the QCApro package provides professional functionality for performing configurational comparative research with Qualitative Comparative Analysis (QCA), including crisp-set QCA, multi-value QCA, and fuzzy-set QCA. It also offers new features and advanced tools for methodological evaluations of QCA. The package can be downloaded from the software page on my website, where further important information is also available.

  • Jan 2016: Article on sensitivity diagnostics for QCA published in Political Analysis 24(1)

    Sensitivity diagnostics rank high on the current agenda of research into Qualitative Comparative Analysis (QCA), and existing studies in this area rely on the technique of exhaustive enumeration. In this article, we introduce the technique of combinatorial computation for evaluating the interaction effects between two problems afflicting data quality and two discretionary parameters on the stability of QCA solutions. Combinatorial computation challenges a hitherto unstated assumption intrinsic to exhaustive enumeration and is vastly superior in terms of efficiency. For more details, visit the article's website.

  • Jan 2016: Comment on Comparative Multilevel Analysis published in Quality & Quantity 50(1)

    In a recent contribution to Quality & Quantity, Denk and Lehtinen (2014) present Comparative Multilevel Analysis (CMA) as an innovative method whereby the effects of contexts can be studied if combined with Qualitative Comparative Analysis (QCA). In contrast, I argue that CMA is not necessary for ascertaining this influence of context. QCA is appreciably more powerful than the authors acknowledge. In repetition of Rohlfing's (2012) verdict on Denk's (2010) earlier version of CMA, I conclude that QCA need not be extended in the direction proposed by Denk and Lehtinen. For more details, visit the article's website.

  • Nov 2015: Article on causal chains and QCA published in Sociological Methods & Research 44(4)

    In a recent article in SMR, Baumgartner and Epple (2014) argue for the superiority of Coincidence Analysis (CNA) over Qualitative Comparative Analysis (QCA) as the former can identify causal chains without generating logical contradictions during the minimization process that arise from the application of the Quine-McCluskey algorithm in QCA. I claim that CNA does not challenge QCA in this respect because the link between QCA and QMC has never been inextricable, and showcase the latter's hitherto unexploited ability to identify causal chain models in configurational data that even include multivalent factors. For more details, visit the article's website.

  • Jul 2015: Article on cna package published in The R Journal 7(1)

    We present cna, a package for performing Coincidence Analysis (CNA). CNA is a configurational comparative method for the identification of complex causal dependencies - in particular, causal chains and common cause structures - in configurational data. After a brief introduction to the method's theoretical background and main algorithmic ideas, we demonstrate the use of the package by means of an artificial and a real-life data set. Moreover, we outline planned enhancements of the package that will further increase its applicability. For more details, visit the article's website.                 

  • Apr 2015: Article on eQMC algorithm published in Journal of Mathematical Sociology 39(2)

    Qualitative Comparative Analysis (QCA) has attracted considerable attention in sociology and political science in recent years. The process of Boolean minimization by means of the Quine-McCluskey algorithm (QMC) is the central procedure in QCA, but QMC's exactitude renders it memory-intensive and slow in processing complex output functions. In this article, we introduce the enhanced QMC algorithm (eQMC) to alleviate these problems. Simulations demonstrate eQMC's superiority in speed and memory performance. For more details, visit the article's website.                                                                                

  • Feb 2015: Article on mvQCA published in Quality & Quantity 49(2)

    Multi-value Qualitative Comparative Analysis (mvQCA) continues to exist under the shadow of crisp and fuzzy-set QCA, a situation to which the lack of support for parameters of fit and intermediate solutions has contributed. This article introduces two innovations. First, the measures of consistency and coverage are generalized. Second, the concept of the intermediate solution is imported. I demonstrate how to exploit these features in the QCA software package. For researchers not using QCA, I explain how to make use of Veitch-Karnaugh maps instead. For more details, visit the article's website.

  • Jan 2015: Exchange on article by Simon Hug published in Qualitative & Multi-Method Research 12(2)

    In a recent article, Hug (2013) criticizes QCA for its reliance on Mill's methods, researchers for having perverted QCA's original goal, and the method itself for being sensitive to data problems. In this comment, I reveal Hug's account of the relation between Mill's methods and QCA as misguided, his assertion that QCA's original purpose has been perverted as a misapprehension of its analytical core, and his warnings that data problems influence solutions as comforting. I also prove several of his results to be incorrect. Furthermore, I expose his "Monte Carlo simulation" as an awkward approach. You can download the full exchange here.

  • Dec 2014: Article on six pitfalls of QCA published in Evaluation Review 38(6)

    Qualitative Comparative Analysis (QCA) has been enjoying increasing levels of popularity in evaluation research. In this article, I seek to raise awareness of six pitfalls with regard to three aspects: case numbers, necessity relations and model ambiguities. I argue that case numbers are irrelevant to the choice of QCA, that necessity is not as simple a concept as is often suggested, and that doubt must be cast on the determinacy of virtually all results presented in past QCA research. I explain the background of these pitfalls and introduce procedures that help avoid them. For more details, visit the article's website.

  • Oct 2014: Article on sensitivity in fuzzy-set relations published in International Journal of Social Research Methodology 17(6)

    The method of fuzzy-set Qualitative Comparative Analysis (fsQCA) has gained in popularity across various disciplines. However, while its methodological development has progressed on a number of fronts, sensitivity diagnostics have only recently been put on the agenda. This article analyses how coverage as an important descriptive statistic in fsQCA is influenced by the interaction between membership function form and crossover threshold choice. It concludes that the influence of membership functions should become part of routine sensitivity checks. For more details, visit the article's website.

  • May 2014: Article on gsQCA published in Sociological Methods & Research 43(2)

    Crisp-set, fuzzy-set and multi-value Qualitative Comparative Analysis (QCA) have emerged as distinct variants of QCA, but textbooks have emphasized their differences rather than commonalities. This article has two objectives. First, it demonstrates that all set types associated with each variant can be combined. Second, but dependent on this first objective, it introduces the concept of the multivalent fuzzy-set variable. This variable type underlies generalized-set Qualitative Comparative Analysis (gsQCA), which subsumes all existing QCA variants as special cases. For more details, visit the article's website.

  • Jul 2013: Article on QCA software published in Social Science Computer Review 31(4)

    The widening landscape of tailored software attests to the success of Qualitative Comparative Analysis (QCA). Users now have the choice between three graphical user (GUI) and three command line (CLI) interface solutions. However, each program possesses some particularities users may not be aware of. We compare the two most common GUIs fs/QCA and Tosmana as well as the CLI QCA. By reanalyzing data from a published work, major differences and similarities with respect to truth table construction, minimization algorithms, and prime implicant chart management are illustrated. For more details, visit the article's website.

  • Jul 2013: Article on QCA package published in The R Journal 5(1)

    We present QCA, a package for performing Qualitative Comparative Analysis (QCA). QCA is becoming increasingly popular with social scientists, but none of the existing software alternatives covers the full range of core procedures. This gap is now filled by QCA. After a mapping of the method's diffusion, we introduce some of the package's main capabilities, including the calibration of crisp and fuzzy sets, the analysis of necessity relations, the construction of truth tables and the derivation of complex, parsimonious and intermediate solutions. For more details, visit the journal issue's website.               

  • Apr 2013: Exchange on mvQCA published in Field Methods 25(2)

    In a contribution to Field Methods, Vink and van Vliet (2009) seek to raise awareness of the potentials and pitfalls of multi-value Qualitative Comparative Analysis (mvQCA). Unconvinced by the technique's distinctness, they question its added value in relation to crisp-set and fuzzy-set QCA on five points. I demonstrate why none of them challenges mvQCA. Two points do not relate to the method, two are based on incorrect reasoning, and one results from a misunderstanding of notational systems. This comment therefore proves the suspicion against mvQCA unjustified. Vink and van Vliet provide a response. For more details, visit the article's issue's website.

  • Nov 2012: Article on QCA package published in Qualitative & Multi-Method Research 10(2)

    The increasing popularity of Qualitative Comparative Analysis (QCA) as a tool for social-scientific inquiry has led to a proliferation of dedicated software. Researchers now have the choice between three graphical (GUI) and three command line interface (CLI) solutions. In this article, we present a brief overview of the QCA software market, following which we introduce the QCA package for the R environment by drawing operational parallels to fs/QCA, the most common GUI software. For more details, visit the article's website.                                                                                                                                 

  • Sep 2012: New book Qualitative Comparative Analysis with R: A User's Guide

    Social science theory often builds on sets and their relations. The development of Qualitative Comparative Analysis (QCA) has given social scientists a formal tool for identifying set-theoretic connections. This book offers the first introduction on how to perform QCA in the R software environment with the QCA package. Developed as a comprehensive solution, QCA provides an unprecedented scope of functionality for analyzing crisp, multi-value and fuzzy sets. Readers are not required to have knowledge of R, but the book assumes an understanding of the fundamentals of QCA. Although mainly written for political scientists, it is also of interest to scholars from other disciplines. To learn more, visit the book's website.