Wikipedia 10K Redux by Reagle from Starling archive. Bugs abound!!!

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Stratified_Sampling

back to [[Survey Sampling]]

:[[Cluster Sampling]] -- [[Multistage Sampling]] -- [[Simple Random Sampling]]

When subpopulations of the population to be studied vary considerably, it is advantageous to sample each subpopulation (stratum) independently and produce a [[Weighted Mean]] that has less variability than the [[Arithmetic Mean]] of a random sample. There are several possible strategies:
#Proportionate allocation uses the same [[Sampling Fraction]] in each of the strata.
#Optimum allocation takes larger samples in the strata with the greatest variability to generate the least possible sampling variance.
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[[Dick Beldin]]