1.4.2.7. - Normalization and Error Bars
The values returned as error bars are those due to counting statistics (the square root of the number of counts). When the counts are derived from the algebraic combination of detector, background and monitor counts, the error bars are calculated using the appropriate propagation of errors formalism. ( P.R. Bevington, Data Reduction and Error Analysis for the Physical Sciences, (McGraw-Hill, New York, 1969), p. 64. )