What is Type A OC curve?

What is an operating characteristic (OC) curve? The operating characteristic (OC) curve depicts the discriminatory power of an acceptance sampling plan. The OC curve plots the probabilities of accepting a lot versus the fraction defective. When the OC curve is plotted, the sampling risks are obvious.

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What distribution is used to determine the OC curve for an attributes sampling plan?

Effect of N, n, and c on the OC curve The Hypergeometric distribution is used to calculate the probability of acceptance for any plan (N, n, c) whereas the Binomial distribution is used for any plan (n, c).

What are Type A and Type B OC curves explain?

OC curves based on lot size, are called Type-A OC curves (hypergeometric distribution). They are closely approximated by the Type-B OC curve which assumes an infinite lot size (binomial distribution). The Type-B OC Curve represents the worse case.

What is an OC curve and what is it used for?

An operating characteristic (OC) curve is a chart that displays the probability of acceptance versus percentage of defective items (or lots).

What are the parameters of OC curve?

The parameters are: the acceptable quality level AQL; the risk α ; the lot tolerance percent defective LTPD; and the risk β . In most situations the objective is to find a sample size n and acceptance number c whose OC curve meets the above parameters.

How many types of OC curve are there?

The statistical quality control theory shows that there are two types of operational-characteristic curves.

What is a Type B OC curve?

The Type-B OC Curve represents the worse case. It has the greatest chance of both accepting bad lots and rejecting good lots. Figure 2: OC Curves of n=13, a=0. Since Type-B OC curves represent the worse case, sampling plans selected based on Type-B OC curves can be used to inspect any lot regardless of size.

How many types of OC curves are there?

What is OC curve in statistics?

The operating characteristic (OC) curve measures the performance of an accepting sampling plan. This curve plots the probability of accepting the lot versus proportion non– conforming.

What is the difference between Type A and Type B OC curve?

Type A and Type B OC Curve Type A curve is always lower than the Type B curve. Type A curve always has less probability of acceptance than Type B curve. As the lot size increases, type A curve approaches Type B curve. If , then both the curves are almost identical.

What is AQL in OC curve?

The user defines the Acceptable Quality Limit (AQL) and the Rejectable Quality Limit (RQL), and the producer’s risk and the consumer’s risk. The OC curve is generated by determining a sample size and an allowable number of failures or defects.

Why do we use OC curve?

The operating characteristic (OC) curve is the primary tool in lot acceptance sampling plans (LASP). They allow data from a sample to be used to draw conclusions about the lot as a whole with defined risks.

What does AQL 0.65 mean?

AQL means the poorest level of quality that is considered acceptable in a particular population or in a pre-defined sample size. For example: “AQL is 0.65%” means “I want no more than 0.65% defective items in the whole order quantity, on average over several production runs with that supplier”.

What does AQL 2.5 mean?

acceptable quality limit
AQL 2.5 means the buyer considers as acceptable quality limit a defect rate of 2.5% of the total order quantity.

What does an AQL of 4.0 mean?

Besides, I assume you have set your AQL at 2.5% for major defects and 4.0% for minor defects. Therefore, here are the limits: the products are accepted if NO MORE than 10 products with major defects AND NO MORE than 14 products with minor defects are found.