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Sample Size (Evidence Rating Element)

A sample is the subset of the entire population that is included in a research study. Typically, all else being equal, a larger sample size leads to increased precision in estimates of various properties of the population. The sample size affects the statistical power of a study and the extent to which a study is capable of detecting meaningful program effects. It is included as an element with Statistical Power in the Scoring Instrument. See Program Review and Rating from Start to Finish for more information.