Many decisions are based on the results of measurements. Faced with a particular customer problem, the laboratory must first set the analytical requirement which defines the performance characteristics that a method must have to solve that problem.

The selected analytical method must be set up correctly, with planned QC, a well documented procedure that is validated and after some time in use an valid estimate of the uncertainty. The ongoing internal quality control and (QC) and proficiency testing (PT) assure that the measurement results (including uncertainty) are of the same quality as at the time of validation. Guidance for this process is given under menu item ANALYTICAL METHOD and additional support under RESOURCES. 

Some guides we  recommend on QC, validation and measurement uncertainty