So sánh phương pháp

	Chọn mẫu có chủ đích trực tuyến	Chọn mẫu có chủ đích	Lấy mẫu chuỗi giới thiệu – Lấy mẫu quả cầu tuyết
Lĩnh vực	Phương pháp luận khảo sát	Phương pháp luận khảo sát	Phương pháp luận khảo sát
Họ	Process / pipeline	Process / pipeline	Process / pipeline
Năm ra đời	1990s–2000s (with growth of internet-based research)	Formalized ~1980–1990	1961
Người khởi xướng	Adaptation of purposive sampling (Patton, 1987) to online/digital research contexts	Michael Quinn Patton (systematic articulation); roots in early qualitative inquiry	Leo A. Goodman
Loại	Non-probability qualitative sampling	Non-probability sampling strategy	Non-probability sampling technique
Công trình gốc	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	Goodman, L. A. (1961). Snowball sampling. Annals of Mathematical Statistics, 32(1), 148–170.
Tên gọi khác	internet-based purposive sampling, web purposive sampling, online criterion-based sampling, digital purposive sampling	judgmental sampling, selective sampling, criterion-based sampling, purposeful sampling	chain-referral sampling, network sampling, respondent-driven sampling, referral sampling
Liên quan	3	4	3
Tóm tắt	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.	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.	Snowball sampling is a non-probability recruitment technique in which initial participants (seeds) refer the researcher to others who meet the study criteria, and those referrals in turn refer further participants. The sample grows incrementally — like a rolling snowball — until the required size or theoretical saturation is reached. It is the method of choice when a target population has no accessible sampling frame, such as undocumented migrants, illicit drug users, survivors of stigmatised experiences, or members of closed professional networks.