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Multilingual Demographic Dictionary, second unified edition, English volume

Primary unit

Multilingual Demographic Dictionary, second unified edition, English vol.
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Primary unit  (PRIMARY unit)


In stratified random sampling 1 the population is divided into a number of strata 2 which are in some sense more homogeneous (134-4) than the population as a whole with respect to the characteristics studied, and a simple random sample (161-4) is drawn in each stratum. Variable sampling fractions (161-5) may be used in the different strata. Multi-stage sampling 3 is a method where the selection of the sample is carried out in several stages. A sample of primary units 4 is first selected and each of these units is then regarded as a population (101-3) from which a sub-sample 5 of secondary units 6 is selected, and the process may be repeated. When there is no good sampling frame, a sample of areas delimited on a map may be selected: this procedure is called area sampling 7.

  • 1. Stratify, v,: divide into strata (plural of stratum) - stratification, n.

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