% Uncertainty Budgets - Auditor wants to see my uncertainty budget represented as a %

[luluthecat]

Hi everyone,

I have an assesor (for 17025 accreditation) coming out and he wants to see my uncertainty budget represented as percentages.

Does anyone have an idea how I would convert this into a percentage?
All my contacts at other cal labs have never heard of this.
The assesor said that my calculations are correct, but he wants to see them as percentages. Does ISO even require the budget to be represented as percentages?

Any suggestions would be very much appreciated!

[Hershal]

Without knowing the parameter(s), it is difficult to say whether your scope is typically expressed in percentages.

Some scopes have parameters that are in fact typically expressed in percentages. As an example, force-compression can and often is expressed as a percentage, but can also have specific numbers for the uncertainty.

Hope this helps a bit.

Hershal

[W. de Jong]

Your assesor may be asking this for his own convenience. We use the document EA-4/02 "expression of uncertainty..~" and it says in 4.9 that table 4.1 is an example. This table contains a contribution to the standard uncertainty but is absolute. For your own convenience you might want to convert that into relative percentages to instantly get an insight on the biggest contributor. But not just to please your assesor.
Btw this might be different for non-european countries, maybe find a equivalent to such a document. But i'm quite sure the ISO17025 says nothing about percentages.

Hope this may be of any help.

BR.

EA-4/02 [270 Kb]: http://www.european-accreditation.or...-4-02rev01.pdf

[JerryStem]

ISO doesn't require it to be expressed in any certain form, to my knowledge. It depends on what you're measuring and how typically it can be expressed.

I hapen to have mine expressed as a percentage for convenience. I don't need a very detailed, minute uncertainty budget. Most of our customers have never heard of MU and the ones that have only need it because QS9K says they do.

I express my MU as a % of the marked value of the thickness standard for coating/plating thickness measurement instruments. I factor in the master standard's tolerance (+/-5%), working std (same), and a few small variables.

I get a fairly large % (8.8%) but it makes sense, A2LA is FINALLY happy (even had a special 1.5 day free visit from an assessor to check us out). and our customers still don't care.

Jerry

[Hershal]

The best advice for scopes is to obtain the ILAC document , available at no cost on the ILAC website. It does not specify percent or number, but does give good guidance on scopes.

http://www.ilac.org

Hershal

[luluthecat]

Thank you everyone for all your help!

I just think I might make it through this A2LA audit!!!