topic Re: How to find AQL and LQ levels from Product Risk Assesment Probabilities? in Discussions

How to find AQL and LQ levels from Product Risk Assesment Probabilities?

qLienceStats — Fri, 01 Nov 2024 12:51:10 GMT

Hello everyone.

I am currently going to conduct a validation and I am a bit lost because normally I am just given a LQ level which I then should work from. But now I need to derive the AQL/LQ level from the Product Risk Assesment due to it is not a standard currently for the company I am a consultant for.

The situation is that I have a team of vision specialist but they do not know when they have achieved their goals which have a attribute respons (not good/good). I want to use LQ level due to we are doing validation which should present the worst batch where AQL is more average batch performance. But I want to first find my AQL level to find my LQ level.

I forexample then have one type a error where I know the following from my Product Risk Assesment:
- P_defect = 1.00E-02 : Probability of occurrence

- P_nd = 1.00E-03 : Probability of non detection

- Severity of harm = 2 (Results in temporary injury or impairment not requiring professional medical intervention.)

How do I find my AQL level based on my P_defect, P_nd and Severity and how can I change it if I want to save money on sampling but still fulfill requirements?

Re: How to find AQL and LQ levels from Product Risk Assesment Probabilities?

MRB3855 — Sat, 02 Nov 2024 16:02:32 GMT

Hi @qLienceStats : Not sure exactly what you are asking. An acceptable AQL and LQ are not "derived". i.e., whether or not the AQL and LQ of a given sampling plan are acceptable or not is not something to be calculated. Example: Say a sampling plan has an AQL of 0.72% and an LQ of 7.6%. Yes, those numbers can be derived...but are they acceptable? That is not a statistical question. Or am I misunderstanding your question?

And how do you know P_defect = 1.00E-02 ?

Re: How to find AQL and LQ levels from Product Risk Assesment Probabilities?

qLienceStats — Sat, 02 Nov 2024 19:16:30 GMT

Hello MRB3855, and thanks for taking the time to respond!

From my understanding then i understand the following

My P_defect = 1.00E-02, i get from my process risk assesment. This probability should though be confirmed in PQ.

My question is: How do i go step-by-step from what is given i my product and process risk assesment to a suitable AQL level?

Re: How to find AQL and LQ levels from Product Risk Assesment Probabilities?

MRB3855 — Mon, 04 Nov 2024 11:00:45 GMT

Hi @qLienceStats : I'm very aware of the statistical details of OC curves, AQL/LQ, etc. However, I'm afraid I can't answer the question of "what is a suitable AQL level" (or LQ level). That strikes me as non-statistical question and outside my area of expertise. i.e., what is suitable for one product/process may not be suitable for another.

Apologies, and I hope others on this site can assist.

That said, there may be something helpful here: https://variation.com/?s=aql

Re: How to find AQL and LQ levels from Product Risk Assesment Probabilities?

Byron_JMP — Thu, 07 Nov 2024 16:26:42 GMT

this add-in would be helpful for what you're trying to do.

https://community.jmp.com/t5/JMP-Add-Ins/JMP-Acceptance-Sampling-Plan-Add-In/ta-p/319677

Unfortunately it looks like the add-in is currently missing. The author might be doing some revisions to it or something.

When it comes back on-line, there is a tool for assessing sets of sampling plans that would be worth looking at.