General guidance is provided for the determination of the major uncertainty contributors in any measurement. These are the commonly encountered sources of uncertainty although some, or all, of them may not be applicable to individual pathology assays.
The sources of uncertainty will depend on each individual measurement process. There are some sources that will be common to all measurements whereas there will be some that are only appropriate for certain input variables. However, even if not deemed to be appropriate the sources which are excluded must be reported as insignificant rather than merely excluded without explanation.
It is important that these sources are defined at the outset of analysis, and that these are clearly defined as being the sources of uncertainty for each and every measurement. The final uncertainty result should quote these sources in the uncertainty budget and document why they are considered as insignificant.
- Definition of the measurand
- Combining two measurands
- Assay variability
- Measurement set-up
- Software and calculations
- Physical constants
Once identified a process of categorisation is performed to make the calculations further down the process more simple