مقایسهٔ روش‌ها

	نمونه‌گیری نظری آزمایشی	نمونه‌گیری گلوله‌برفی
حوزه	روش‌شناسی پیمایش	روش‌شناسی پیمایش
خانواده	Process / pipeline	Process / pipeline
سال پیدایش	1967 (theoretical sampling origin); compound practice formalized in qualitative methodology literature	1961
پدیدآور	Glaser & Strauss (theoretical sampling); pilot study concept is longstanding in research methodology	Leo A. Goodman
نوع	Qualitative sampling strategy with pilot phase	Non-probability sampling technique
منبع بنیادین	Glaser, B. G., & Strauss, A. L. (1967). The Discovery of Grounded Theory: Strategies for Qualitative Research. Aldine. ISBN: 978-0202302607	Goodman, L. A. (1961). Snowball sampling. Annals of Mathematical Statistics, 32(1), 148–170.
نام‌های دیگر	pilot-phase theoretical sampling, exploratory theoretical sampling, preliminary theoretical sampling	chain-referral sampling, network sampling, respondent-driven sampling, referral sampling
مرتبط	3	3
خلاصه	Pilot theoretical sampling applies the logic of theoretical sampling — selecting participants based on emerging concepts and theory — within a deliberate pilot or preliminary phase of a study. Rather than committing immediately to a full sampling strategy, the researcher conducts a small initial round of data collection and analysis to test whether theoretical sampling is feasible, to refine the sensitizing concepts guiding participant selection, and to identify whether the field is productive before full-scale data collection begins.	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.