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Plans for Very Low Fraction Nonconforming

Summary: Existing sampling plans are not very efficient in situations where the fraction of nonconforming items is near 0.0001. In such cases the statistician must resort to 100% inspection, which still will not guarantee 100% conforming product since inspection error can introduce an error almost as great as the original fraction nonconforming. Skip-lot sampling is rarely an acceptable alternative to customers, who usually prefer inspection of every shipped lot. This paper suggests an inspection policy combining the ideas of several sampling strategies and guaranteeing against both undesirable levels of Average Outgoing Quality (AOQ) and poor quality on a lot-to-lot basis. The method is based on observing the number of conforming items between nonconforming ones and shifting to 100% inspection when certain criteria are not met.

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  • Topics: Sampling
  • Keywords: Sampling,Average Outgoing Quality (AOQ),Sampling plans
  • Author: Pesotchinsky, Leon
  • Journal: Journal of Quality Technology