مقایسهٔ روش‌ها

	نمونه‌گیری هدفمند تطبیقی	نمونه‌گیری گلوله‌برفی
حوزه	روش‌شناسی پیمایش	روش‌شناسی پیمایش
خانواده	Process / pipeline	Process / pipeline
سال پیدایش	1980s–1990s	1961
پدیدآور	Rooted in Patton's purposive sampling typology; adaptive dimension from iterative qualitative inquiry traditions	Leo A. Goodman
نوع	Qualitative sampling strategy	Non-probability sampling technique
منبع بنیادین	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.
نام‌های دیگر	iterative purposive sampling, emergent purposive sampling, adaptive qualitative sampling, dynamic purposive sampling	chain-referral sampling, network sampling, respondent-driven sampling, referral sampling
مرتبط	5	3
خلاصه	Adaptive purposive sampling is a qualitative strategy in which the researcher begins with explicitly stated, theory-driven selection criteria and then deliberately revises those criteria as data collection proceeds and new understanding emerges. Unlike fixed purposive sampling — where criteria are locked in before fieldwork — the adaptive variant treats the sampling frame as a working hypothesis that is refined in response to early findings, enabling the study to follow the evidence into unexpected but analytically important directions.	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.