Repetitive group sampling plans with double specification limits

Abstract

This paper considers variables repetitive group sampling plans for the lot acceptance when a quality characteristic has double specification limits beyond which an item is considered as defective. The quality characteristic is assumed to follow a normal distribution with unknown mean and known or unknown standard deviation. The design parameters of the variables repetitive group sampling plan are obtained for the known and the unknown standard deviations so as to satisfy the producer's and consumer's risk at the respectively specified quality levels. Symmetric and asymmetric cases are dealt with, which are based on the fraction defectives by the lower and the upper specification limits.