Hi Peter,
Welcome to the IFSQN forums.
Historic quality control data can be used to calculate the uncertainty of each Laboratory test method with a 95% confidence of a result being within +/- x amount of the result.
Measurement uncertainty is important when assessing whether a test result is within legal or safety limits as the uncertainty of the result could take the result outside of acceptable limits.
Appearance and organoleptic are likely to be more subjective and cross-checked against “a standard”.
The example given in the previous post is a bit unclear, I would explain as follows:
If the legal limit is a minimum of 10 with the uncertainty +/- 1 then the minimum reading should be 11.
If the legal limit is a maximum of 10 with the uncertainty +/- 1 then the maximum reading should be 9.
Kind regards,
Tony
Edited by Tony-C, 31 January 2023 - 07:02 AM.