手法を比較

	Qualitative Comparative Analysis	Most Different Systems Design
分野	Political Science	Political Science
系統	Process / pipeline	Process / pipeline
提唱年	1987	1970
提唱者	Charles C. Ragin	John Stuart Mill (method of agreement); Przeworski & Teune (systems framing)
種類	Set-theoretic, configurational comparative method	Small-N comparative case-selection design
原典	Ragin, C. C. (1987). The Comparative Method: Moving Beyond Qualitative and Quantitative Strategies. Berkeley: University of California Press. ISBN: 9780520058347	Przeworski, A., & Teune, H. (1970). The Logic of Comparative Social Inquiry. New York: Wiley-Interscience. ISBN: 9780471701422
別名	QCA, csQCA, fsQCA, Configurational comparative method	MDSD, Most different cases design, Mill's method of agreement, Diverse systems design
関連	3	3
概要	Qualitative Comparative Analysis (QCA) is a set-theoretic, configurational method that identifies which combinations of conditions are necessary or sufficient for an outcome across a set of cases. Developed by Charles Ragin, it treats each case as a configuration of set memberships, builds a truth table of all logically possible combinations, and uses Boolean algebra to minimize them into the simplest expressions that account for the outcome. It bridges qualitative case knowledge and cross-case generalization, embracing causal complexity through conjunctural causation, equifinality, and asymmetry.	The most different systems design (MDSD) is a small-N comparative strategy that selects cases that differ on as many background characteristics as possible yet share the same outcome. If wildly dissimilar cases nonetheless converge on the same result, the explanation cannot lie in the many features on which they differ — it must lie in whatever they have in common. Grounded in John Stuart Mill's method of agreement and named by Przeworski and Teune, it is the mirror image of the most similar systems design and a staple of comparative politics.