The process or result of separating a sample into subsamples according to specified criteria such as age or occupational groups. [L. stratum, layer, + facio, to make]
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strat·i·fi·ca·tion .strat-ə-fə-'kā-shən n arrangement or formation in layers or strata <\stratification of epithelial cells>
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strat·i·fi·ca·tion (strat″ĭ-fĭ-kaґshən) [L. stratum layer + facere to make] 1. disposal in layers. 2. in statistical analysis, separation of a sample into subsamples on the basis of specified criteria, in order to control for the effects of confounding variables.Medical dictionary. 2011.