Estimating measurement uncertainty

Estimating measurement uncertainty

Examples of guides to the expression of uncertainty in measurement

Examples of guides to the expression of uncertainty in measurement

Five steps to evaluate measurement uncertainty:

  1. Analyse measurement system. Error budget
  2. Correct for known measurement errors
  3. Evaluate (standard) measurement uncertainties with methods of type A alternatively type B
  4. Combine standard measurement uncertainties => uc
  5. Expand measurement uncertainty => U = k• uc

Measurement result = ŷ ± U

_______________________________________________________________________________________

Budget of Measurement Errors & Uncertainties

Error & uncertainty budget

Error & uncertainty budget

Where possible, an error budget should be later verified with empirical results from e.g. method validation, internal control and laboratory comparisons. A lack of agreement can depend amongst others on

  • underestimates of variations and uncertainties from different error sources;
  • as yet unidentified error sources.

If the empirical results differ significantly from the error budget, then it should of course be revised with new estimates, the introduction of further components in the error model and/or modified functions of input quantities in the error model. If further error sources cannot be identified, then it may be necessary to use an error model for the final measurement result (that is not decomposed in terms of various input quantities) as can be estimated from empirical results.

__________________________________________________________________________________________

Combine standard measurement uncertainties => uc

Combing standard uncertainties

Combining standard uncertainties

Advertisements

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s

%d bloggers like this: