So sánh phương pháp

	Lấy mẫu trường hợp lệch trực tuyến	Chọn mẫu có chủ đích trực tuyến
Lĩnh vực	Phương pháp luận khảo sát	Phương pháp luận khảo sát
Họ	Process / pipeline	Process / pipeline
Năm ra đời	1990s–2000s (deviant case strategy); online variant ~2000s–2010s	1990s–2000s (with growth of internet-based research)
Người khởi xướng	Patton, M. Q. (deviant case strategy); online adaptation via web-based qualitative research practice	Adaptation of purposive sampling (Patton, 1987) to online/digital research contexts
Loại	Purposive qualitative sampling strategy (online variant)	Non-probability qualitative sampling
Công trình gốc	Patton, M. Q. (2002). Qualitative Research and Evaluation Methods (3rd ed.). Sage. [Chapter 5: Purposeful Sampling, deviant/extreme case strategy, pp. 231-234] ISBN: 978-0761919711	Patton, M. Q. (2002). Qualitative Research and Evaluation Methods (3rd ed.). Sage Publications. ISBN: 978-0761919711
Tên gọi khác	online extreme case sampling, internet-based deviant case sampling, online outlier sampling, web-based atypical case sampling	internet-based purposive sampling, web purposive sampling, online criterion-based sampling, digital purposive sampling
Liên quan	5	3
Tóm tắt	Online deviant case sampling is a purposive qualitative sampling strategy in which the researcher deliberately seeks out and recruits participants who represent extreme, unusual, or outlier instances of the phenomenon under study, using online channels such as forums, social media, specialist communities, or digital registries. It inherits the logic of Patton's deviant (extreme) case sampling and applies it in internet-mediated research contexts where rare or hard-to-reach atypical cases can be located more efficiently than through face-to-face methods.	Online purposive sampling applies the logic of criterion-based participant selection to digital recruitment channels — including social media platforms, online communities, email lists, and research recruitment websites. Researchers intentionally seek individuals who possess the characteristics, experiences, or expertise directly relevant to the research question, using internet-based tools to locate and screen them. The method preserves the defining feature of purposive sampling — deliberate selection based on fitness for purpose — while leveraging the reach and accessibility of online environments.