2.5. Uncertainty analysis
2.5.7. |
Standard and expanded uncertainties |
**2*s(i)**2)}](mpc56.gif)
where k is chosen to be the t1-α/2,ν critical value from the t-table with ν degrees of freedom. For large degrees of freedom, k = 2 approximates 95 % coverage.
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2.
Measurement Process Characterization
2.5. Uncertainty analysis
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| Definition of standard uncertainty |
The sensitivity coefficients and standard deviations are combined by
root sum of squares to obtain a 'standard uncertainty'. Given
R components, the standard uncertainty is:
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| Expanded uncertainty assures a high level of confidence |
If the purpose of the uncertainty statement is to provide coverage
with a high level of confidence, an expanded uncertainty is
computed as
where k is chosen to be the t1-α/2,ν critical value from the t-table with ν degrees of freedom. For large degrees of freedom, k = 2 approximates 95 % coverage. |
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| Interpretation of uncertainty statement |
The expanded uncertainty defined above is assumed to provide a
high level of coverage for the unknown true value of the measurement
of interest so that for any measurement result, Y,
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