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	Enkelt slumpmässigt urval	Klusterurval
Ämnesområde	Surveymetodik	Surveymetodik
Familj	Process / pipeline	Process / pipeline
Ursprungsår	Early 20th century; systematized by Cochran 1953/1977	Early-to-mid 20th century; canonical treatment 1953/1977
Upphovsperson	William Gosset, Jerzy Neyman, and formalized by William Cochran	Formalized by William G. Cochran; roots in early 20th-century U.S. Census Bureau survey practice
Typ	Probability sampling design	Probability sampling design
Ursprungskälla	Cochran, W. G. (1977). Sampling Techniques (3rd ed.). John Wiley & Sons. ISBN: 978-0471162407	Cochran, W. G. (1977). Sampling Techniques (3rd ed.). Wiley. ISBN: 978-0471162407
Alias	SRS, unrestricted random sampling, equal-probability sampling, EPSEM	cluster random sampling, area sampling, one-stage cluster sampling
Närliggande	6	5
Sammanfattning	Simple random sampling (SRS) is the foundational probability sampling method in which every unit in the population has an equal and independent chance of being selected. Because selection is governed purely by chance, SRS eliminates systematic bias, supports unbiased estimation of population parameters, and provides the statistical baseline against which all more complex probability designs are evaluated.	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.