Do ISO GUM reported uncertainties always require NIST traceability?
July 11, 2011 10:31 AM Subscribe
ISO GUM acceptable measurements w/o NIST traceability possible? Weight and length measurements always require NIST traceability for reported results (if following ISO 17025)? More inside...
posted by nickerbocker to Technology (16 answers total) 1 user marked this as a favorite
I'm suppose to be the uncertainty guy. I have two problems that I face while trying to provide an appropriate uncertainty analysis for a test we will be performing. I need to give a reasonable estimate of uncertainty for a weight and length measurement associated with the test setup.
I have a number of scales, and a number of tape measures but none of these would be considered "recently calibrated" with NIST traceability.
My question is, is NIST traceable calibration always necessary?
For the length measurement, I can take multiple measurements with multiple tape measures and calculate and report a mean and variance of these measurements (Type A analysis).
Similarly, I have a number of dumbbells (non-calibrated weights) that I can make observations on multiple scales and compare the outputs to one another. Again, I can perform a Type A analysis on the uncertainty of these measurements.
Would NIST traceability be required at all? The Test Standard does not report a required accuracy of these measurements. Since that is the case, our policy is to follow ISO GUM practices and report a conservative estimate of accuracy. Thanks for your help!