Two New Independent Mixed Sampling Plans for Inspecting a Product with Linear Profiles

Acceptance-sampling plans have been widely used to decide whether an inspection lot should be accepted or rejected. From an economical point of view, a mixed sampling plan is better than the attribute sampling plan. In this paper, we present two new independent mixed sampling plans based on the yield index for linear profiles. The first plan is based on the traditional mixed sampling scheme, and the second plan is based on the modified mixed sampling scheme with marginal quality. A nonlinear optimization model determines the plan parameters that the criterion is to meet the specification of two points on the operating characteristic curve. We found that the number of profiles required in the first stage is smaller than in the second stage. The results confirm that the independent plan with marginal quality is superior to the independent plan and the single and double sampling plans by attributes in terms of average sample number. Two real examples are used to illustrate the proposed plans.