Uncertainty analysis is an evolving subject area. The following advice represents normal good practice.

The Eight Main Steps To Evaluating Uncertainty

1. Decide what you need to find out from your measurements. Decide what actual measurements and calculations are needed to produce the final result.
2. Carry out the measurements needed.
3. Estimate the uncertainty of each input quantity that feeds in to the final result (Type A and Type B estimates). Express all uncertainties in similar terms (standard uncertainty u).
4. Decide whether the errors of the input quantities are independent of each other.
5. Calculate the result of your measurement (including any known corrections for things such as calibrations).
6. Find the combined standard uncertainty from all the individual aspects.
7. Express the uncertainty in terms of a coverage factor together with the size of the uncertainty level, and a state of confidence. (Expanded uncertainty)
8. Write down the measurement result and the uncertainty, and state how you got both of these.

Taking each step in turn:

 

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Good practice online modules

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• Measurement uncertainty
• Introducing uncertainty
• Basics of uncertainty analysis