# QCA: A Package for Qualitative Comparative Analysis

## Description

The package QCA contains functions to perform Qualitative Comparative Analysis, complemented with a graphical user interface. It implements the comparative method as first described by Ragin (1987), and extended by Cronqvist and Berg-Schlosser (2009) and Ragin (2000, 2008). QCA is a bridge between the qualitative and quantitative research methodologies, making use of the qualitative procedures in a systematic, algorithmic way (therefore increasing the “confidence” in the results, as understood by quantitative researchers).

The Quine-McCluskey minimization algorithms implemented in this package are mathematically exact, as described by Dusa (2007b), Dusa (2010), Dusa and Thiem (2015) and Dusa (2017). They all return the same, relevant set of prime implicants for csQCA (binary crisp sets QCA), mvQCA (multi-value QCA) and fsQCA (fuzzy-sets QCA).

The package also showcases functionality for other types of QCA like tsQCA (temporal QCA), see Caren and Panofsky (2005), Ragin and Strand (2008), and more recently also causal chains similar to those from the package cna (see Ambuehl et all 2015).

The results of the QCA package are consistent with (and sometimes even better than) the results of the other software packages for QCA, most notably fs/QCA by Ragin and Davey (2014) and Tosmana by Cronqvist and Berg-Schlosser (2009). A comparison of several such software is provided by Thiem and Dusa (2013).

More recent versions bring major improvements and additions, most notably: - a new minimization algorithm called CCubes (Consistency Cubes), that is hundreds of times faster than the previous eQMC; - conjunctural directional expectations; - extension to categorical data.

## Details

Package: | QCA
Version: | 3.22
Date: | 2024-03-15
License: | GPL (>= 3)

## References

Ambuehl, M. et all (2015) A Package for Coincidence Analysis (CNA), R Package Version 1.0-3 [Computer Program] URL: https://cran.r-project.org/package=cna.

Caren, N.; Panofsky, A. (2005) “TQCA: A Technique for Adding Temporality to Qualitative Comparative Analysis.” Sociological Methods & Research vol.34, no.2, pp.147-172.

Cronqvist, L. (2011) Tosmana: Tool for Small-N Analysis, Version 1.3.2.0 [Computer Program]. Trier: University of Trier.

Dusa, A. (2007a) “User manual for the QCA(GUI) package in R”. Journal of Business Research vol.60, no.5, pp.576-586.

Dusa, A. (2007b) Enhancing Quine-McCluskey. WP 2007-49, COMPASSS. URL: http://www.compasss.org/wpseries/Dusa2007b.pdf.

Dusa, A. (2010) “A Mathematical Approach to the Boolean Minimization Problem.” Quality & Quantity vol.44, no.1, pp.99-113.

Dusa, A. (2017) “Consistency Cubes: A Fast, Efficient Method for Boolean Minimization.” unpublished working paper on ResearchGate, DOI: RG.2.2.36359.19361/4

Dusa, A.; Thiem, A. (2015) “Enhancing the Minimization of Boolean and Multivalue Output Functions With eQMC” Journal of Mathematical Sociology vol.39, no.2, pp.92-108.

Ragin, C.C. (1987) The Comparative Method: Moving beyond Qualitative and Quantitative Strategies. Berkeley: University of California Press.

Ragin, C.C. (2000) Fuzzy-Set Social Science. Chicago: University of Chicago Press.

Ragin, C.C. (2008) Redesigning Social Inquiry: Fuzzy Sets and Beyond. Chicago: University of Chicago Press.

Ragin, C.C.; Strand, S.I. (2008) “Using Qualitative Comparative Analysis to Study Causal Order: Comment on Caren and Panofsky (2005)”. Sociological Methods & Research vol.36, no.4, pp.431-441.

Ragin, C.C.; Davey, S. (2014) fs/QCA: Fuzzy-Set/Qualitative Comparative Analysis, Version 2.5 [Computer Program]. Irvine: Department of Sociology, University of California.

Thiem, A.; Dusa, A. (2013) “Boolean Minimization in Social Science Research: A Review of Current Software for Qualitative Comparative Analysis (QCA).” Social Science Computer Review vol.31, no.4, pp.505-521.

## Author

Adrian Dușa
Department of Sociology
University of Bucharest
dusa.adrian@unibuc.ro
Maintainer:
Adrian Dușa