So sánh phương pháp

	Lấy mẫu trường hợp lệch chuẩn thử nghiệm	Chọn mẫu có chủ đích
Lĩnh vực	Phương pháp luận khảo sát	Phương pháp luận khảo sát
Họ	Process / pipeline	Process / pipeline
Năm ra đời	2002 (Patton codification); pilot study tradition mid-20th century	Formalized ~1980–1990
Người khởi xướng	Patton (deviant case sampling); pilot study methodology attributed broadly to pre-main-study practice traditions	Michael Quinn Patton (systematic articulation); roots in early qualitative inquiry
Loại	Purposive sampling variant applied in pilot phase	Non-probability sampling strategy
Công trình gốc	Patton, M. Q. (2002). Qualitative Research and Evaluation Methods (3rd ed.). Sage. [Chapter 5: Sampling Strategies, pp. 230–246 on deviant/extreme case sampling] ISBN: 978-0761919711	Patton, M. Q. (1990). Qualitative Evaluation and Research Methods (2nd ed.). Sage. ISBN: 978-0803937796
Tên gọi khác	pilot extreme case sampling, pilot outlier sampling, pilot atypical case sampling, pilot deviant-case pilot sampling	judgmental sampling, selective sampling, criterion-based sampling, purposeful sampling
Liên quan	2	4
Tóm tắt	Pilot deviant case sampling is a purposive sampling strategy applied during a pilot phase in which participants are deliberately selected because they represent extreme, unusual, or atypical instances of the phenomenon under study. Rather than seeking representative participants for the pilot run, the researcher intentionally recruits outlier cases to probe the boundaries of research instruments, interview guides, or data collection protocols before the main study begins.	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.