Even if GR&R studies cannot be applied in their purest form, you must be confident that your data represents what it is supposed to. An ‘MSA Drilldown’ is a structured approach for doing that, by understanding and checking the ‘pedigree’ of the source data against the operational definition.
The four key steps of an MSA drilldown are:
1) Drilldown through the data to find its source components
2) Challenge each component in terms of possible measurement error (bias or precision)
3) For each potential source of error, decide if it’s acceptable
4) If it is acceptable, then document your decision and move on with the project
A tree diagram is the best way to structure the output of an MSA Drilldown, as shown below: