Self-test 11

When is it reasonable to use the ISO GUM modeling (type “g” in the box) and when Nordtest (type “n” in the box) approach for estimating the measurement uncertainty?

a) There is a lot of measured data available|including measurements with certified reference materials. 

b) The principle of the measurement procedure is poorly understood and there are possibly many unknown uncertainty sources. 

c) There is no reliable certified reference material or reference procedure for estimating the reference value. 

d) The principle of the measurement procedure is well understood and uncertainty sources are easy to estimate quantitatively. 

e) In the lab a reliable reference sample is available and analyzed with a number of parallel measurements on different days. A routine sample is analyzed by the same procedure over the time period of one year|making a number of measurements.