ISO 2859-4-2002 pdf free download.Sampling procedures for inspection by attributes – Part 4: Procedures for assessment of declared quality levels.
7.2 Rules for contradicting a declared quality level
The number of sample items inspected shall be equal to the sample size given by the plan.
— If the number of nonconfoi’ming items found in the sample is less than or equal to the limiting number (L), the declared quality level has not been contradicted.
— If the number of nonconforming items found in the sample is greater than the limiting number (L), the declared quality level has been contradicted.
EXAMPLE If, in the examp4e considered in 6.2, two or fewer nonconforming items are found in the sample of 125, the sample result does not contradict the DOL of 0,65 % nonconforming items. LI three or more nonconforming items are found, the sample evidence contradicts the DOt…
If the sample size equals or exceeds the size of the entity under investigation, then the DOL shall be verified by comparing it to the actual quality level determined by inspecting all items in the entity.
7.3 DisposItion of nonconforming Items
Any nonconforming items found in the sample shall not be returned to the rest of the items unless the nonconforming items are bought to a conforming condition and applicable administrative rules are followed.
8 Further information
8.1 Curves showing approximate probability of contradiction
The curves shown in Figure 1 indicate the approximate probability that a sample result will lead to contradiction of the declared quality level. The curves give the approximate probability of contradiction as a function of the quality ratio.
The curves in Figure 1 refer to situations where the declared quality level is one of the preferred values. For non- preferred values of DQL the information in Figure 1 does not apply.
8.2 Tables indicating discriminatory ability
Tables 5 to 7 provide additional information about the probabilities of contradicting incorrect declared quality levels for different values of the quality ratio.
For each individual sampling plan, Tables 2 to 4 show the value of the limiting quality ratio (LQR) that corresponds to a 10% risk of failing to contradict the declared quality level. This LOR together with the information pesented in Tables 5 to 7 may be used to assess the discriminatory ability of each sampling plan.
Tables 2 to 4 also show the probability that the sample result (falsely) will contradict the declared quality level when the actual quality level is equal to the DOL.
The values in Tables 2 to 7 have been determined under the assumption that the sample size is only a small fraction of the entity under investigation. The values in these tables are valid when the sample size is less than or equal to 1110 of the entity.
When the sample size is a larger fraction of the entity under investigation, the actual discriminatory ability will be better than indicated by the values in Tables 2 to 7. In particular. the actual limiting quality ratio will be smaller than the value indicated in Tables 2 to 4, and moreover, the actual probability of falsely contradicting a correct DQL will also be smaller than that indicated in Tables 2 to 4.ISO 2859-4 pdf download.