Chain-Deferred Inspection Plans

Abstract

The paper proposes plans that improve on existing chain and deferred sampling plans. The plans are mixed in the sense that they combine elements from both chained and deferred plans. This combination gives an operating characteristic curve closer to that of the traditional double sampling plan than either the simple chain or the simple deferred inspection plan when there is a trend in process quality. The plans require fewer items to be sampled than the traditional double sampling plans and have a delay in the decision only where there are indications that quality is poor. The relative ease with which these plans can be made compatible with the double sampling plans in the MIL‐STD‐105D and some other similar schemes is noted.