手法を比較

	専門家インタビュー	ケーススタディリサーチ（Case Study Research）	Delphi Method	フォーカスグループリサーチ
分野	質的手法	質的手法	質的手法	質的手法
系統	Process / pipeline	Process / pipeline	Process / pipeline	Process / pipeline
提唱年	1970s–1990s (methodologically systematized)	1984 (seminal codification)	1963	1940s (sociological origin); modern applied form from the 1980s–1990s
提唱者	Meuser & Nagel (methodological codification, 1991); roots in elite interview tradition (Dexter, 1970)	Robert K. Yin (systematised in Case Study Research, 1984)	Norman Dalkey & Olaf Helmer (RAND Corporation)	Robert K. Merton (sociological precursor, 1940s); popularised in applied research by Richard A. Krueger
種類	Qualitative research method	Qualitative research design	Structured iterative expert-elicitation process	Qualitative data collection method
原典	Bogner, A., Littig, B., & Menz, W. (Eds.). (2009). Interviewing Experts. Palgrave Macmillan.	Yin, R.K. (2018). Case Study Research and Applications: Design and Methods (6th ed.). Sage. ISBN: 978-1506336169	Dalkey, N. & Helmer, O. (1963). An Experimental Application of the Delphi Method to the Use of Experts. Management Science, 9(3), 458-467.	Krueger, R.A. & Casey, M.A. (2014). Focus Groups: A Practical Guide for Applied Research (5th ed.). Sage. ISBN: 978-1483365244
別名	elite interview, key informant interview, specialist interview	Vaka Çalışması (Case Study), case study design, case study methodology	Delphi Yöntemi, Delphi technique, expert consensus method	focus group discussion, FGD, group interview, Odak Grup Araştırması
関連	6	5	5	6
概要	The expert interview is a qualitative method in which researchers conduct in-depth, semi-structured conversations with individuals who hold specialised knowledge, experience, or decision-making authority in a defined field. Unlike general population interviews that target subjective lived experience, expert interviews treat respondents as proxies for a broader institutional or professional knowledge domain. The method is widely used in policy research, organisational studies, science and technology studies, and applied social sciences to map tacit professional knowledge, reconstruct decision processes, and triangulate documentary sources.	Case study research is a qualitative research design that investigates a specific phenomenon, individual, group, organisation, or event in depth within its real-world context. Systematised by Robert K. Yin in 1984, it supports single-case and multiple-case designs and draws on multiple data sources — interviews, observation, documents, and artefacts — to build a rich, contextualised account of a bounded unit.	The Delphi method is a structured, iterative survey technique developed by Norman Dalkey and Olaf Helmer at the RAND Corporation in 1963 for eliciting and converging expert opinion on complex topics where empirical data are unavailable or insufficient. It collects independent judgements from a geographically dispersed expert panel over multiple anonymous rounds, feeding aggregated results back to participants after each round so they can revise their views in light of the group's collective position.	Focus group research is a qualitative data-collection method in which a trained moderator guides structured discussions with homogeneous groups of six to ten participants to explore ideas, attitudes, and perceptions on a defined topic. Developed from sociological roots in the 1940s and systematised for applied research by Krueger and Casey, the method leverages group interaction as a data source — revealing not just what people think, but how they negotiate and articulate views in a social setting.