representative sample

A sample resulting from a sampling plan that can be expected to adequately reflect the properties of interest of the parent population. A representative sample may be a random sample or, for example, a stratified sample, depending upon the objective of sampling and the characteristics of the population. The degree of representativeness of the sample may be limited by cost or convenience.
PAC, 1990, 62, 1193 (Nomenclature for sampling in analytical chemistry (Recommendations 1990)) on page 1202