مقایسهٔ روش‌ها

	نمونه‌گیری هدفمند چندسطحی	نمونه‌گیری خوشه‌ای
حوزه	روش‌شناسی پیمایش	روش‌شناسی پیمایش
خانواده	Process / pipeline	Process / pipeline
سال پیدایش	1980s–1990s	Early-to-mid 20th century; canonical treatment 1953/1977
پدیدآور	Derived from Patton's purposive sampling framework; formalized in multi-site qualitative and mixed-methods research	Formalized by William G. Cochran; roots in early 20th-century U.S. Census Bureau survey practice
نوع	Non-probability sampling strategy	Probability sampling design
منبع بنیادین	Patton, M. Q. (2002). Qualitative Research and Evaluation Methods (3rd ed.). Sage. ISBN: 978-0761919711	Cochran, W. G. (1977). Sampling Techniques (3rd ed.). Wiley. ISBN: 978-0471162407
نام‌های دیگر	hierarchical purposive sampling, nested purposive sampling, multi-tier purposive sampling, multi-site purposive sampling	cluster random sampling, area sampling, one-stage cluster sampling
مرتبط	5	5
خلاصه	Multi-level purposive sampling applies purposive selection criteria at two or more nested levels of a research hierarchy — for instance, first selecting sites or organizations, then selecting participants within each site. This layered approach allows researchers to align the theoretical logic of purposive sampling with the real-world structure of complex, hierarchical populations, making it especially valuable in multi-site qualitative studies and mixed-methods research.	Cluster sampling is a probability sampling technique in which the population is divided into naturally occurring groups (clusters), a random sample of clusters is selected, and all — or a random subset of — members within each selected cluster are studied. It is especially practical when a complete population list is unavailable or when units are geographically dispersed, making individual random selection prohibitively expensive. One-stage cluster sampling surveys every member of selected clusters; two-stage designs add a second random draw within clusters.