Design of variable repetitive group sampling plan on operating characteristics indexed by quality loss

The quality of lots has been conservatively evaluated based on attribute properties such as the proportion or number of non-conforming items in the lot. On the other hand, Taguchi proposed a concept of quality loss as a measure to evaluate the quality of items based on variable properties instead of attribute properties. Incidentally, Robert proposed the attribute repetitive group sampling plan on operating characteristics instead of the attribute single sampling plan on operating characteristics. In this way, the attribute repetitive group sampling plan can be understood as a more efficient sampling plan from the viewpoint of comparison of the required number of samples, since the required number of samples in this plan is less on average than that of the traditional attribute single sampling plans. In this article, for the purpose of improving the efficiency of the variable sampling plan based on quality loss proposed by Arizono et al., the variable repetitive group sampling plan is considered. Specifically, we show the design procedure for finding out inspection criterions and s1ample size under the desired operating characteristics indexed by quality loss. By illustrating that average sample number in the inspection is reduced, the effectiveness of the proposed sampling plans is verified.