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ISRO IPRC Technical Assistant Mechanical held on 21/04/2018

Option 3 : OC curve

ISRO VSSC Technical Assistant Mechanical held on 09/06/2019

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**Explanation:**

Acceptance sampling:

Acceptance sampling is the process of **evaluating a portion of the product/material in a lot** for the purpose of **accepting or rejecting the lot **as either conforming or not conforming to a quality specification.

Operating Characteristic (OC) curve:

The operating characteristic curve for an attribute **sampling plan is a graph of fraction defective in a lot against the probability of acceptance.**

For any fraction defective p in a submitted lot, The OC curve shows the probability Pa that such a lot will be accepted by the sampling plan.

In a** sampling plan**, three** parameters **are specified,

**N** = lot size from which the samples are drawn,

**n** = sample size,** **

**C** = acceptance number

It means, takes a random sample of n from a lot of N if the sample contains more than C defective, rejects the lot otherwise accept the lot.

There are two terms on the OC curve:

Producer's risk:

- If the quality is good still from the sampling plan some lots are rejected the producer has to suffer.
- The producer risk is the probability of rejecting a good lot that otherwise would have been accepted.

Consumer's or Purchaser's risk:

- if the quality is bad still from the sampling plan some lots are to be accepted the consumer will suffer.
- Consumer's risk is the probability of defective lots being accepted which otherwise would have been rejected.