I'm trying not to sort all parts. If I know I have a defect rate of .65% how many pieces would I have to check to find 1 defective piece. Thanks for your help.
I'm afraid you are wishing for the impossible.
At a .0065 defect rate and 13,000 pcs in the lot there are 85 defective pieces in the lot. do you want to find them all?
How do you KNOW there is an exactly .65% defective rate in the lot? is this defect randomly distributed or do they cluster/group together when they are created?
the math I gave you works if you only want to find 1 defective part then you will find it in a
random sample of 460 parts 95% of the time. of course it's possible that you will find none or 2. why do you only want to find 1? dont' you want to find all of them? if you dont' want to find all of them then just ship the lot.
we need to be reasonable here.
are the defects bad?
should they be removed from the lot? if so then you must sort the entire lot. if they aren't "that bad" then let it go without any sort. if you are only trying to convince yourself that the lot is truly at least .65% defective then a sample of 461 will detect at least 1 defective part 95% of the time and you will have proof that the lot is probably .65% defective. but remember that there is still a 5% probability that you miss a defective part and then ship a .65% defective lot.
statistics is not the portal to getting out of doing the hard work...answer the questions in bold above for yourself.