Economic Choice of Sample Size for Sampling Inspection Plans

Conventional single sample inspection plans for investigating the quality of batches of manufactured items take, at best, only an informal regard for any tangible prior information on batch qualities (for example, as provided by the process curve) or cost structure. Decision theory methods have been proposed to incorporate these factors directly, but they have seldom been brought to the level of day‐to‐day application. This paper extends such work by considering, for a particular cost structure but no prior information, how to actually choose the sampling plan (sample size, and critical number of defective items for rejecting the batch) which is economically most desirable. The theoretical results are illustrated by numerical tabulation over a representative range of parameter values, to demonstrate the practical form of the cost optimal inspection plans.