AQL and RQL Calculation for Variables Sampling Plan

[WLN]

Hi,
Does anyone know how to calculate AQL for variable sampling plan?

My problem is, I do not know how c comes about in variable sampling plan. Please help.

Thank you very much.
Regards,
Neoh

 

[Rick Goodson]

Neoh,

Your question is to complex for a simple answer in this forum. You need to look at a good text on sampling plans. Try Statistical Quality Control by Grant and Leavenworth. In Part Three look at chapter 11 on the Fundamental Concepts in Scientific Sampling and then chapter 15 Systems for Acceptance Sampling by Variables. The authors go into a fair amount of detail regarding attribute plans and the equivalent variables plan.

Rick

 

[Stan Hilliard]

Hi Neoh,

There is a 20 page tutorial on this subject at www.samplingplans.com/modern3.htm. You can print it out.

Stan Hilliard

 

[AviGeva]

Neoh,
1. You do not really calculate AQL in variable sampling but estimate the percent deffectives.
2. You do not need "c" (acceptance number ) in variable sampling. You just compare the calculated value Ql or Qu to the tabulated one and make the decission.
I think that Rick is right, you must have a good textbook on variable sampling or take a course. It is not so easy to get an "off the sleev" answer.

Avi

 

[Cristi?nC]

Stan: I've tried unsuccessfully to reach that URL. Is it something wrong?

Thanks in advance!

 

[Rick Goodson]

Cristián,

I had the same problem opening the site. Use the main address, www.samplinplans.com, and you will get in. You can then click on 'tutorial on sampling' to get to the information you are looking for.

Regards,

Rick

 

[Stan Hilliard]

The URL that I posted doesn't work because trailing decimal points and commas foul it up. It's fixed now.

Stan Hilliard

 

[DonkeyKong]

RQL

Im looking for a standard to back up some RQL figures......I may be wrong but I believe that the Z1.4 standard only addresses AQL and not RQL....
Can anyone shed some light on this topic...is there a standard ou their I can purchase to validate my findings.
Confused...
CS:thedeal:

 

[Rick Goodson]

DonkeyKong,

It was way to long ago when I was a young QE, but we will try to get the old gray cells working again....

Rejectable Quality Level (RQL) is used interchangeably with Limiting Quality Level (LQL) or Lot Tolerance Percent Defective (LTPD). The tables you want are Dodge-Romig Sampling Inspection Tables. You need an estimate of the incoming quality level (process average) and you need an RQL or LQL level and lot size. The tables are set to be used with rejected lots being 100% inspected which then gives you the Average Outgoing Quality Level (AOQL) you are looking for.

Hope this helps,

Rick