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Nuclear Safeguards Education Portal

Systematic sampling

The process of selecting samples in a repeated pattern, such as every 11th item or at fixed time intervals, from a continuing process. The selection of the first item determines the selection of all other items; therefore the first item must be selected at random unless it is known that the variability from item to item is negligible. Systematic sampling can result in bias if the population characteristics vary systematically in the sequence or vary in a cyclic manner.