From: Stan Hilliard shilliard@samplingplans.com
Date: 02 Oct 2002
Time: 14:57:56
YOU SAID: For example if I have a lot containing 200,000 units. what is n and Ac?
MY ANSWER: When you develop sampling plan based on the oc curve, under conditions where the binomial distribution applies (n<20,000 for your example) the lot size does not figure into it. There are only four values that effect n and Ac. They are AQL, RQL, Alpha, and Beta. Those four values specify two points on the oc curve:
The producer's point addresses the rejecting of AQL lots: (AQL,1-Alpha)
The consumer's point addresses the acceptance of RQL lots: (RQL,Beta)
See www.samplingplans.com/usingoccurves.htm for a more thorough explanation.
You also mentioned the difference between the "design alpha" and "actual Alpha". Note that Ac and n are always whole numbers. When you specify the (design) alpha, there may not be whole numbers n & Ac that matches it exactly. The "actual Alpha" is the value that corresponds to the decision rule (n & Ac) after rounding to whole numbers.