From: Stan Hilliard hilli004@tc.umn.edu
Date: 31 Oct 1998
Time: 11:34:27
Remote Name: 160.94.26.135
Hello Tom,
Here is an example of a sampling scheme for auditing inventory accuracy based on the inventory's value. I think it is more rational and economical than Mil-Std-105E.
Software program TP105 will be used here because it does not use lot size, and it uses both producer's and consumer's risks. Develop two sampling plans that differ only in that the RQL of plan 2 is 1/2 that of plan 1. (Nomenclature note: RQL=LQ=LTPD):
Plan 1: (for lower value areas, lower sample size than Plan 2) Using decimal fractions: Producers point = (alpha=0.05, AQL=0.01) Consumers point = (beta =0.05, RQL=0.12)
Plan 2: (for higher value areas, higher sample size than Plan 1) Using decimal fractions: Producers point = (alpha=0.05, AQL=0.01) Consumers point = (beta =0.05, RQL=0.06)
Note that RQL=0.06 is 0.12/2.
The decision rules from TP105 are: Plan 1: n=37, c=1, the sequential the minimum n to accept is 25. Plan 2: n=129, c=3, the sequential minimum n to accept is 57.
I hope this is a good starting point. You can modify the producers and consumers points to attain OC Curves(use TP105) that are most suitable for your type of inventory.
Sincerely, Stan Hilliard