
424 A First Course in Quality Engineering
We want to point out here that in quality control literature (e�g�, Duncan
1974), the OC curve we dened above is referred to as the “Type-B” OC curve,
because the probabilities are calculated using the binomial distribution on
the assumption that sampling is done from “large” lots� If the sampling is
not from large lots, hyper-geometric distribution should be used to calculate
the probabilities of acceptance� The OC curve is then called the “Type-A” OC
curve� In our discussion here, we will assume that the sampling is always
from large lots and that all the OC curves calculated are Type B� A large ...