From: Stan Hilliard
Date: 17 Oct 2001
Time: 12:08:18
Hi Rodin,
> ...A SAMPLE IS INDICATIVE OF THE POULATION?
You need to refine your goal numerically before it can be solved numerically. That is, to be able to calculate a sample size for making a confidence statement you must specify a margin of error. For example when you are sampling for percent defective, the margin of error is the maximum difference between the sample percent defective and the population percent defective. If you do not specify it numerically, it is not possible to calculate a sample size. Software program Audit Sample Planner deals with this issue:
www.samplingplans.com/software_me
You can find more information by searching for the word "confidence" (without the quotes) by going to the top of this forum and clicking on "Search for Words". You will get more than 40 hits.
Perhaps you want to accept/reject the population rather than to make a confidence statement. In that case you need to calculate a decision rule -- which is another word for an acceptance sampling plan. In that case you need to specify and Acceptable Quality Level (AQL) and a Rejectable Quality Level (RQL). Software for this is here:
www.samplingplans.com/software_oc.htm
For the theory of application of acceptance sampling, start here:
www.samplingplans.com/usingoccurves.htm
Stan Hilliard