What does an OC curve show?
The OC (Operating Characteristics) Curve shows how well the acceptance sampling plan works, that is, it shows the probability of accepting lots coming in with various amount of defective items. The use of sampling plans involves risks to the buyer and seller.
What is OC curve in quality control?
An operating characteristic (OC) curve is a chart that displays the probability of acceptance versus percentage of defective items (or lots).
What is the probability of acceptance for the producer in an ideal OC curve?
The graph of this performance is known as operating characteristic curve. Fig. 60.2 below shows an ideal O.C. curve where it is desired to accept all lots having 3% or less defectives, and to reject all lots having more than 3% defectives.
What is producer risk?
Producer’s risk is the probability that a good product will be rejected as a bad product by the consumer. It calculates the probability of loss from (1) rejecting a batch which, in fact, should have been accepted, or (2) accepting a batch that, in fact, will be rejected by the customer.
What is an OC curve quizlet?
An operating characteristic (OC) curve is a graph that measures. The probability of accepting a lot for different quality levels with a specific sampling plan. The expected number of defective items that will pass on to the customer with a sampling plan is known as the. average outgoing quality.
How many types of OC curves are there?
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 are producer’s risk and consumer’s risk?
The error of rejecting a good-quality lot creates a problem for the producer; the probability of this error is called the producer’s risk. On the other hand, the error of accepting a poor-quality lot creates a problem for the purchaser or consumer; the probability of this error is called the consumer’s risk.
What is producer’s risk and consumer’s risk in quality control?
The risk that product of unsatisfactory quality will be accepted (Consumer’s Risk) The risk that good quality product will be rejected (Producer’s Risk).
What is consumer’s and producer’s risk?
This means that there are two types of risks that can occur: The risk that product of unsatisfactory quality will be accepted (Consumer’s Risk) The risk that good quality product will be rejected (Producer’s Risk).
How do you calculate producer risk?
α = P(Reject batch when p = p1)=1 − L(p1): the Producer’s Risk. β = P(Accept batch when p = p2) = L(p2): the Consumer’s Risk. Of course the Producer really cares about rejecting the batch when p ≤ p1, but taking p = p1 is conservative as the probability is always lower for p
What is the purpose of acceptance sampling?
Acceptance sampling is a statistical measure used in quality control. It allows a company to determine the quality of a batch of products by selecting a specified number for testing. The quality of this designated sample will be viewed as the quality level for the entire group of products.
How is the OC curve generated?
The OC curve is generated by determining a sample size and an allowable number of failures or defects. Figure 1 is an OC curve with an AQL of 0.9 (percent defect of 0.1), a RQL of 0.8, producer’s risk of 0.1, consumer’s risk of 0.1, sample size of 86 and acceptance number of 12 (maximum number of failures allowed in the sample).
Is there an OC curve for lots with more than 3% defectives?
In this curve, all lots with less than 3% defectives have a probability of acceptance of 100%, while all lots with more than 3% defectives have a probability of acceptance as 0%. However such a plan does not exist in reality. Graph 60.3 is an OC curve for a sampling plan with n = 50 and C = 1.
What is the OC curve of a sampling plan?
A sampling plan that discriminated perfectly between good and bad lots would have an OC curve that was vertical; that is, it would follow the dashed lines of Graph 60.4. For all lots having percent defectives to the left of the dashed line, the probability of acceptance is 100.
What does the OC curve show about the discriminating power?
If the actual quality is good, then there should be a high probability of acceptance, but if the actual quality is poor, then the probability of acceptance should be low. Thus in this way the OC curve shows how well a given sampling plan discriminates. The discriminating power of any sampling plan depends largely on the size of the sample.