Сравнение на методи

	Клъстерно извадково изследване	Пропорционално клъстерно извадково изследване
Област	Методология на проучванията	Методология на проучванията
Семейство	Process / pipeline	Process / pipeline
Година на възникване	Early-to-mid 20th century; canonical treatment 1953/1977	1950s–1960s
Създател	Formalized by William G. Cochran; roots in early 20th-century U.S. Census Bureau survey practice	Formalized by William G. Cochran and Leslie Kish
Тип	Probability sampling design	Probability sampling design
Основополагащ източник	Cochran, W. G. (1977). Sampling Techniques (3rd ed.). Wiley. ISBN: 978-0471162407	Cochran, W. G. (1977). Sampling Techniques (3rd ed.). John Wiley & Sons. ISBN: 978-0471162407
Други названия	cluster random sampling, area sampling, one-stage cluster sampling	PPS cluster sampling, proportional-to-size cluster sampling, size-proportional cluster sampling, probability proportional to size sampling
Свързани	5	6
Резюме	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.	Proportional cluster sampling selects naturally occurring groups (clusters) from a population with probability proportional to each cluster's size, so that larger clusters have a higher chance of selection while every individual element retains an equal overall inclusion probability. This design efficiently handles large, geographically dispersed populations and is the backbone of national health, education, and social surveys worldwide.