Given a formula with an absolute error in of , the absolute error is . The relative error is . If , then
(1) |
where denotes the mean, so the sample variance is given by
(2) |
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(3) |
The definitions of variance and covariance then give
(4) |
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(5) |
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(6) |
(where ), so
(7) |
If and are uncorrelated, then so
(8) |
Now consider addition of quantities with errors. For , and , so
(9) |
For division of quantities with , and , so
(10) |
Dividing through by and rearranging then gives
(11) |
For exponentiation of quantities with
(12) |
and
(13) |
so
(14) |
(15) |
If , then
(16) |
For logarithms of quantities with , , so
(17) |
(18) |
For multiplication with , and , so
(19) |
(20) |
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(21) |
For powers, with , , so
(22) |
(23) |
REFERENCES:
Abramowitz, M. and Stegun, I. A. (Eds.). Handbook of Mathematical Functions with Formulas, Graphs, and Mathematical Tables, 9th printing. New York: Dover, p. 14, 1972.
Bevington, P. R. Data Reduction and Error Analysis for the Physical Sciences. New York: McGraw-Hill, pp. 58-64, 1969.
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