Q: If repeatability and reproducibility are high, it is a positive output, but high repeatability and reproducibility will give high uncertainty from Equation 1:
uncertainty = sqrt (repeatability^2 + reproducibility^2)
Could you explain to me why it looks like it is contradictory?
A: One wishes to have the repeatability and reproducibility as “low” as possible, hopefully in single digits for well-behaved tests on consistent materials. With this in mind, the uncertainty will be low. Please note that the uncertainty in the test result is not used to approve or reject a product on-site. However, questions will be raised if the uncertainty for a test is high and the test result does not meet the specification values within a few percentage points of the target. In some cases, owners and construction quality assurance (CQA) inspectors are considering a tolerance or range for acceptance.