Please help me with Measurement Uncertainty (MU) Calculations?

[amanbhai]

i have to calculate the Measurement Uncertinty for every test.
can anyone help me with measurement Uncertinty calculations.
any material like slides or presentation kind of thing would help.

thank you.

[Gert Sorensen]

This link may help you

[reynald]

You forgot the link

[Gert Sorensen]

I'll try again

http://metrologyforum.tm.agilent.com/unc_guide.shtml

[Benjamin28]

Hello Amanbhai,

I'd like to first ask what type of testing you will be evaluating for UOM? If you're a materials testing laboratory and you follow well recognized procedure, i.e. ASTM documents, it is generally accepted that these specify limits to the major contributors of measurement uncertainty. In this case you would be interested in checking the uncertainty of your calibrated instruments which you use in the test.

If you have your instruments calibrated by an outside source, accredited lab, the lab should be able to supply you with the measurement uncertainty for that instrument. If you, however, calibrate your instruments in house you will unfortunately have to go through the process of creating a UOM budget for each instrument type. You can fortunately generalize your budgets to a type of device rather than do a UOM calculation for every instrument...i.e. you can calculate MU on your calipers as a whole, pending that the instruments are all of the same type, such as digital 0-6" calipers, calibrated on the same reference gage blocks, same nominal temperatures, etc...

As you may have seen from some of my various posts in this forum I was recently working on this same task, and I would like to say that the best plan of attack is to seek training from a pro in the field. I used a combination of the guides GUM, TN1297s, etc...and a package document from HN Metrology Consulting which details the use of the PUMA method to calculating MU. This training module was actually from a training course supplied by the forementioned consultant that my manager had attended, but I did find it quite useful.

I think, as you set out on the road of measurement uncertainty, that you will find there is no REALLY simple way of doing this. But, once you intially get the hang of it, it becomes easier on the next one.

I'm going to stop here and let you answer as to what you'll be evaluating for MU...will it be for calibrations of measurement devices?

[skappesser]

Learning MU is not a short-term project. I got some basic MU training from the American Association for Laboratory Accreditation (A2LA) a few years ago. The first thing the instructor said was to get good at it "you must practice it every day for a long time". He was right. I did not feel confident in my calculations for about a year. The A2LA seminar course was a good start for me - every penny I spent was worth it. Google them and check out their website. A2LA has some helpful info at their website too - spend some time there...
Also, I like to refer to UKAS M3003 "The Expression of Uncertainty and Confidence in Measurement". It is more user friendly than ANSI/NCSL Z-540-2 ("The GUM") ...UKAS is the United Kingdom Accreditation Service. You can download that at this link http://www.ukas.com/information_centre/publications.asp
(Scroll down until you find it - it is there.)
I'll also recommend Stephanie Bell's "Beginner's Guide to Uncertainty in Measurement". It's free, here is the link http://www.npl.co.uk/cgi-bin/guide_info.pl?guide=11
Fair winds and following seas - oh prince of metrology - the door you have opened is indeed a heavy one.

[Ken K]

This is the guide I used for our testing lab.

http://www.a2la.org/guidance/est_mu_testing.pdf

[Wesley Richardson]

In addition to the sources and documents already mentioned, ANSI/NCSL Z540-2 is another good document for measurement uncertainty.

NCSLI Store

Wes R.