Let the true value of a quantity be and the measured or inferred value . Then the relative error is
defined by

where is the Absolute Error. The relative error of the Quotient or Product of a number of quantities is less than or equal to the Sum of their relative errors. The Percentage Error is 100% times the relative error.

**References**

Abramowitz, M. and Stegun, C. A. (Eds.).
*Handbook of Mathematical Functions with Formulas, Graphs, and Mathematical Tables, 9th printing.*
New York: Dover, p. 14, 1972.

© 1996-9

1999-05-25