CHOICE OF DOUBLE SAMPLING PLANS BASED ON PRIOR DISTRIBUTIONS AND COSTS.

Approximate models for the optimum economic design of double sampling plans for attributes are presented. Total cost is assumed to consist of sampling costs, the cost of accepting defective items, and the cost of rejecting good items. This cost is minimized relative to a specified prior distribution of process fraction defective. Models are developed for situations in which rejected lots are either scrapped or subjected to 100 percent inspection with defective items removed. Other variations of the basic model include the incorporation of restrictions among the sampling plan parameters, which may be helpful in improving administrative efficiency, and the use of curtailment on the second sample. Numerical examples for the various models are presented.