مقایسهٔ روش‌ها

	نمونه‌گیری موردی انحرافی مبتنی بر میدان	نمونه‌گیری هدفمند
حوزه	روش‌شناسی پیمایش	روش‌شناسی پیمایش
خانواده	Process / pipeline	Process / pipeline
سال پیدایش	1980s–1990s (purposive/deviant case sampling literature)	Formalized ~1980–1990
پدیدآور	Michael Quinn Patton; Yvonna Lincoln & Egon Guba	Michael Quinn Patton (systematic articulation); roots in early qualitative inquiry
نوع	Purposive qualitative sampling strategy	Non-probability sampling strategy
منبع بنیادین	Patton, M. Q. (2002). Qualitative Research and Evaluation Methods (3rd ed.). Sage Publications. ISBN: 978-0761919711	Patton, M. Q. (1990). Qualitative Evaluation and Research Methods (2nd ed.). Sage. ISBN: 978-0803937796
نام‌های دیگر	field deviant case sampling, outlier case sampling in field research, extreme case sampling in fieldwork, in-situ deviant case sampling	judgmental sampling, selective sampling, criterion-based sampling, purposeful sampling
مرتبط	5	4
خلاصه	Field-based deviant case sampling is a purposive strategy that deliberately selects cases deviating markedly from an established pattern or norm, with data collected through direct fieldwork — observation, in-situ interviews, and ethnographic engagement — in the participants' natural settings. By studying outliers on-site, researchers gain contextually grounded insight into why and how certain cases diverge from the typical pattern.	Purposive sampling is a non-probability strategy in which the researcher deliberately selects participants, documents, or cases that are information-rich with respect to the research question. Rather than drawing units at random, the researcher applies explicit criteria aligned with the study's purpose, maximising the depth and relevance of the data collected. It is the default sampling logic in most qualitative research designs and is also used in mixed-methods and applied evaluative work.