Case Study Research Design: Theory, Typology, Implementation, and Quality in Social Science Inquiry

Case study research design is one of the most widely used and most frequently misunderstood research strategies in the social, educational, management, and applied sciences, offering researchers a systematic framework for conducting intensive, contextually grounded investigation of bounded real-world phenomena through multiple sources of evidence. This paper provides a comprehensive, critically informed, and practically oriented methodological review of case study research design, tracing its intellectual development from clinical and sociological case analysis in the early twentieth century through the foundational frameworks of Yin (1984, 2009, 2014, 2018), Stake (1995, 2006), and Merriam (2009), the philosophical defence by Flyvbjerg (2006, 2011), the typological and abductive extensions by Thomas (2011), the political science comparative case study tradition of Lijphart (1971), Przeworski and Teune (1970), and George and Bennett (2005), the critical realist case study framework of Pawson and Tilley (1997), and the configurational cross-case analysis of Ragin (2004) and Rihoux and Ragin (2009). The paper systematically addresses the definitional and epistemological foundations of case study research; a comprehensive typology of eight case study design variants intrinsic, instrumental, collective, exploratory, explanatory, descriptive, critical/extreme, and embedded; the critical concept of the unit of analysis and case boundedness; principles of case selection including Seawright and Gerring's (2008) seven selection strategies; the twelve-step case study research protocol; evidence collection from multiple sources and the chain of evidence principle; analytic strategies including pattern matching, explanation building, replication logic, and process tracing; quality criteria drawing on both Yin's positivist-adjacent framework and Lincoln and Guba's constructivist criteria; ethical considerations in case study research; disciplinary applications across education, health, management, policy, and digital governance; and a systematic comparison of case study with experiment, survey, ethnography, and grounded theory. Six structured tables consolidate historical, typological, procedural, quality, and comparative information. Recent developments including critical realist case study, qualitative comparative analysis (QCA), digital and platform governance case studies, and AI ethics case analysis are critically assessed. The paper argues that case study research is not a residual design chosen when experiments are impractical but a methodologically rigorous strategy uniquely suited to research questions that require understanding how and why complex, context-dependent phenomena unfold in the real world. Keywords: Case study research, research design, Yin, Stake, Flyvbjerg, unit of analysis, analytic generalisation, replication logic, process tracing, qualitative comparative analysis, bounded system