So sánh phương pháp

	Lấy mẫu trường hợp điển hình	Lấy mẫu chuỗi giới thiệu – Lấy mẫu quả cầu tuyết
Lĩnh vực	Phương pháp luận khảo sát	Phương pháp luận khảo sát
Họ	Process / pipeline	Process / pipeline
Năm ra đời	1980s (systematized in Patton 1990/2002)	1961
Người khởi xướng	Michael Quinn Patton	Leo A. Goodman
Loại	Purposive qualitative 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	Goodman, L. A. (1961). Snowball sampling. Annals of Mathematical Statistics, 32(1), 148–170.
Tên gọi khác	typical case selection, modal case sampling, representative case sampling, average case sampling	chain-referral sampling, network sampling, respondent-driven sampling, referral sampling
Liên quan	5	3
Tóm tắt	Typical case sampling is a purposive strategy in which the researcher deliberately selects cases that represent what is ordinary, normal, or most common within a target group. Rather than seeking outliers or the widest possible variation, the goal is to illustrate and communicate what a typical experience, program, or phenomenon looks like to stakeholders or audiences unfamiliar with it. The strategy is widely used in qualitative evaluation research and program reporting.	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.