Proposal of a variable two-stage sampling inspection plan for assuring operating characteristics regarding quality loss

The quality loss proposed in studies by Taguchi (1985, 1986) has been recognized as a new evaluation measure of quality instead of using the proportion of nonconforming items known as the traditional evaluation measure of quality. In recent years, various kinds of acceptance sampling inspection plans for assuring lot quality under the concept of the quality loss have been developed. In this paper, we propose a variable two-stage sampling inspection plan based on the quality loss as a new type of double sampling inspection plan that is terminated at finite sampling inspection from the viewpoint of practical usefulness. At the same time, reducing the average sample number required for sampling inspection is considered in the newly developed variable two-stage sampling inspection plan. The design procedure for the developed sampling inspection plan is established, and then usefulness of the sampling inspection plan is shown through numerical comparison.