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2.
Measurement Process Characterization
2.5. Uncertainty analysis 2.5.5. Propagation of error considerations
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| Case: Y=f(X,Z) |
Standard deviations of reported values that are functions of
measurements on two variables are reproduced from a paper by H. Ku
(Ku).
The reported value, Y is a function of averages of N measurements on two variables. |
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 of  ,
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Note: Covariance term is to be included only if there is a reliable estimate |
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Note: this is an approximation. The exact result could be obtained starting from the exact formula for the standard deviation of a product derived by Goodman (1960). |
= standard dev of X;
= standard dev of Z;
= covariance of X,Z