Uncertainty vs. TAR/TUR

[Bryan]

I'd like some thoughts on when I can disregard calculating uncertainty.
As an arbitrary limit I have decided that if I am meeting 4:1 accuracy ratio I leave it at that, lesser amounts then I will state an uncertainty.
Is this consistent with the intent of 17025?  Granted specific customer requirements may dictate otherwise but for my own equipment it seems acceptable to me.

[RFCAL]

Unfortunately, to comply with 17025, you must do Uncertainty Calculations for EVERYTHING.An inspector will not accept TUR.

[Wilk]

Unfortunately, to comply with 17025, you must do Uncertainty Calculations for EVERYTHING.An inspector will not accept TUR.

Thats not a completly accurate statement.  "TUR" being defined as "Test Uncertainty Ratio" would mean there are uncertainties available as they would be needed to get a ratio.  This is acceptable by some, but not all of the accrediting bodies I believe.  "TAR" or "Test Accuracy Ratio" on the other hand is not accepted by any of the AB's.  Not sure who is your AB, but most of them have additional policies on top of 17025 that you must also comply with.  A further defined tracebility requirement is usually one of these documents.  The answer to your question will probably be in that document.

[RFCAL]

A2LA will not accept TUR/TAR or 4:1 / 10:1 for us older guys.At least they wouldn't accept them 2 years ago.

[skidaddle skaduski]

lol.. yeah, and check out some of those "TUR's"  lmao.  Or, for a better laugh.

[CalDude]

I always enjoyed finding a calibration certificate with full uncertainty analysis on a parameter that was not on the scope of accreditation from  A2LA, but they still use the logo for that cert. Should that test show a tar our can they just list their uncertainties and not care?

[djshepp21]

   I'm pretty sure A2LA's logo policy is very clear about this...as should that cal house's quality manual.  If memory serves me right, if they are calibrating to ISO 17025 and using A2LA's logo, any parameters under test that isn't within their scope of accredidation should be identified as such.  There's nothing wrong with doing the additional uncertainty analysis for those test, but they cannot claim that parameter as being within their scope on the certificate.

Anyone have anything else to add to that?  Or did I sum it up correctly?

[HarryBee]

.. .. . . ... . bwahahahahahah.  No.. no.. I have a better one.  How about when the standards listed on the certificate are no where close to 4:1 and sometimes 1:1.  I love seeing those certs.

To the OP, if your quality manuals don't state you need to do uncertainties then you don't have to, I don't think, unless your accreditation requires it.