From: Stan Hilliard
Date: 29 Nov 2001
Time: 12:56:47
Brian,
The software program TP414 will calculate the sample size and decision limit(s) and OC Curves for the mean of a variable like PWL. The OC Curve is in the form of Probability of Acceptance -Vs- PWL. See www.samplingplans.com/programtp414.htm
TP414 can calculate the plan and oc curve from AQL, RQL, alpha, and beta.
TP414 can also calculate AQL and RQL from a sample size, decision limit(s), alpha, and beta.
TP414 does not calculate alpha and beta from the other parameters directly, but you can enter sample size and decision limit(s) and read the appropriate points from the oc curve.
A sampling plan for the mean PWL would be one-sided with RQL < AQL (high is good). The decision limit will be units of PWL.
All sampling plans for the mean require input of a known standard deviation. This is the historical within-lot (as opposed to long-range) standard deviation. It can be calculated from the average range (using control chart tables) or by pooling the standard deviations from individual lots.
You can see examples of the output of TP414 for sampling plans for the mean at www.samplingplans.com/outputvariablesmean.htm
TP414 can write its output to a file, which can then be imported into Excel. The columns of oc curve tables will convert to columns in Excel. The same applies to the decision rules of sequential sampling plans.
Stan Hilliard