Stratified sampling is recommended to be used when the population is known to have several subdivisions (i.e., locations) which may give different results for the quality characteristics measured. The Agency expects that no significant differences should exist between in-process locations that could affect finished product quality. Between- and within- location variability is a critical component of finished product quality and therefore should be evaluated. Please refer to ASTM E27096 and ASTM E28107 for further guidance on establishing acceptance criteria for a stratified sampling plan.
