Lot quality assurance sampling: single- and double-sampling plans.

Lot quality assurance sampling (LQAS) was originally developed for industrial applications. This article discusses the extension of its application to a public health setting. When resources must be allocated to several communities based on whether or not each exceeds a target proportion of members with a characteristic, a sampling scenario arises which is different to the standard parameter estimation scenario. LQAS is an efficient procedure for sampling in this instance. Under certain conditions, double sampling may further enhance the efficiency of an LQAS plan. LQAS is discussed and illustrated by examples, and the theoretical foundations of single and double lot quality assurance sampling are presented. Examples of sample size and critical value tables are also presented.