On Cumulative Conforming Type of Control Charts for High Quality Processes Under Sampling Inspection

Control charts for high quality processes based on counting cumulative conforming items have attracted a lot of attention recently. However, such charting procedures usually apply when items are inspected one by one. There are situations that products are inspected sample by sample for practical or economic reasons. In such situations, the application of conventional cumulative conforming type of control charts based on the assumption of geometric or negative binomial distribution is challenged. To solve the related problem, in this paper we propose a new cumulative conforming type of control chart, called CCS (cumulative conforming samples) chart. The ANI (average number of items inspected) performance of CCS chart is examined. The advantage of CCS chart is discussed. Furthermore, the issue of correlation within samples is also addressed. The effect of correlation on the performance of CCS chart is investigated.