Multiple Dependent State Sampling Plan Based on Process Capability Index

This paper extends the idea of multiple dependent state sampling plans to the case of using process capability index when the quality characteristic of the product follows the normal distribution. The plan parameters are determined using the optimization process with minimum values of sample size so that the specified producer's risk and consumer's risk should be satisfied simultaneously for given values of acceptable quality level and limiting quality level in terms of fraction defective beyond two specification limits. The plan parameters are determined under symmetric and asymmetric cases of fraction defective. The advantage of the proposed plan is discussed over the single variable sampling plan. A real example is presented to illustrate the proposed plan in practice.