[Lot quality assurance sampling: methods and applications in public health]

Lot Quality Assurance Sampling (LQAS), developed to meet industrial quality control needs, has been applied to health surveys. The WHO used this method to assess immunization coverage. The sampling strategy was developed to classify lots as acceptable or unacceptable. Lot sampling is an efficient, simple and time-efficient procedure for quality assurance. Under certain conditions, efficiency can be improved with double sampling. We describe the method and its theoretical basis and illustrate applications of LQAS in epidemiological surveillance and quality control of medical records. The advantages and disadvantages of this method are presented.