Vertaile menetelmiä

	Lumipallo-otanta	Maksimivariaation otanta
Tieteenala	Kyselytutkimuksen metodologia	Kyselytutkimuksen metodologia
Menetelmäperhe	Process / pipeline	Process / pipeline
Syntyvuosi	1961	1985 (Lincoln & Guba); elaborated 1990–2002 (Patton)
Kehittäjä	Leo A. Goodman	Lincoln & Guba; systematised by Michael Quinn Patton
Tyyppi	Non-probability sampling technique	Purposive qualitative sampling strategy
Alkuperäislähde	Goodman, L. A. (1961). Snowball sampling. Annals of Mathematical Statistics, 32(1), 148–170.	Patton, M. Q. (2002). Qualitative Research and Evaluation Methods (3rd ed.). Sage. Chapter 5: Purposeful Sampling. ISBN: 978-0761919711
Rinnakkaisnimet	chain-referral sampling, network sampling, respondent-driven sampling, referral sampling	maximum variation sampling, maximum diversity sampling, MVS, heterogeneous sampling
Liittyvät	3	5
Tiivistelmä	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.	Maximum variation sampling is a purposive qualitative sampling strategy in which the researcher deliberately selects cases that span the widest possible range of variation on dimensions central to the study. The goal is not statistical representation but the identification of common patterns that cut across diverse cases as well as the documentation of the unique ways each context shapes the phenomenon under investigation.