Optimal np control charts for concentrated sampling inspection

This article presents an optimal algorithm for the np control chart design. The objective is to maximize the effectiveness of the np chart, on the condition that the false alarm rate is held at a specified level. The effectiveness is measured by the out-of-control ATS (average time to signal). The optimization algorithm can be applied to the concentrated sampling inspection, which is more suitable to those manufacturers whose output is very large. The concentrated sampling inspection means picking and inspecting a sample of size n for every h output units. Each sample consists of units produced at the same time (or as closely as possible). Usually consecutive units of production are preferred in manufacturing industry.