Most Different Systems Design
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.
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Method map
The neighbourhood of related methods — select a node to explore.
Sources
- Przeworski, A., & Teune, H. (1970). The Logic of Comparative Social Inquiry. New York: Wiley-Interscience. ISBN: 9780471701422
- Seawright, J., & Gerring, J. (2008). Case Selection Techniques in Case Study Research: A Menu of Qualitative and Quantitative Options. Political Research Quarterly, 61(2), 294–308. DOI: 10.1177/1065912907313077 ↗
- Gerring, J. (2007). Case Study Research: Principles and Practices. Cambridge: Cambridge University Press. ISBN: 9780521676564
How to cite this page
ScholarGate. (2026, June 22). Most Different Systems Design (Comparative Method of Agreement). ScholarGate. https://scholargate.app/en/political-science/most-different-systems-design
Which method?
Set this method beside its closest kin and read them side by side — the library lays the books on the table; the choice is yours.
- Most Similar Systems DesignPolitical Science↔ compare
- Process TracingPsychometrics↔ compare
- Qualitative Comparative AnalysisPolitical Science↔ compare