Recitation 8 OC CURVES AOQ

Review of parameters N:Lot size n1: Sample size on the first sample c1: Acceptance # on the first sample r1: Non-acceptance # on the first sample n2: Sample size on the second sample c2:Acceptance number for both samples r2: Non-acceptance number for both samples

100 Pa: Percent of Lots accepted. 100Po: Percent non-conforming Procedure: One value 100Po assumed and the other calculated.

Difference between two types of curves: TYPE A AND TYPE B TYPE B Curves: Lots come from a continouos stream of product, therefore the calculations are based on infinite lot size. (Binomial for evaluating, but approx. To poisson) TYPE A: Probability of accepting an isolated lot. (Hypergeometric used to calculate the acceptance probabilities)

OC Curve - Operating Characteristic Curve The OC curve shows how the probability of acceptance (y-axis) depends on the quality level (bottom axis).

Question 1

Producer’s Risk Producer’s risk : α= Probability of non- acceptance of a conforming lot. Refelected on the OC curve as Pa=1- α AQL(Acceptable Quality Level): Max. Percent of nonconforming that can be considered satisfactory for the purposes of accepting sampling.

Consumer’s Risk β: Probability of accepting a non-conforming lot. Usually given as Probability of acceptance. Usually given as 0.10.

Average Outgoing Quality:Average Outgoing Quality: 100*po(Pa) Quality that leaves the inspection operation. Without rectification: AOQ same as incoming quality In rectification: Average outgoing quality is always better than the incoming quality.

Question 2

Question 3