Variables sampling inspection scheme for resubmitted lots based on the process capability index Cpk

This paper attempts to develop a sampling inspection scheme by variables based on process performance index for product acceptance determination, which examines the situation where resampling is permitted on lots not accepted on original inspection. The equations for plan parameters, the required sample size and the corresponding critical value, are derived based on the exact sampling distribution rather than an approximation approach hence the decisions made are more accurate and reliable. Moreover, the efficiency of the proposed variables resubmitted sampling plan is evaluated and compared with the existing variables single sampling plan. For illustrative purpose, an example is presented to demonstrate the use of the derived results for making a decision on product acceptance determination.

► A variables resubmitted sampling plan based on Cpk is developed for lot sentencing. ► The proposed sampling plan is derived based on the exact sampling distribution. ► The efficiency of the proposed variables resubmitted sampling plan is examined. ► The required sample size and the corresponding critical value are provided. ► For practical purpose, an example is presented to illustrate the applicability.