Expression for uncertainty intervals handling skewness when the relative standard uncertainty is independent of the measurand level

Abstract Uncertainty intervals for many measurement results are typically reported as symmetric around the measured value. However, at large standard uncertainties (> approx. 15 %–20 %), it is necessary to consider asymmetry of uncertainty intervals. Here, an expression calculating handling when relative independent measurand level presented. The based on implementation a power transformation ( $${x}^{B}$$ x B ) in order achieve that have and approximate normal distribution. then calculated transformed space back-transformed original space. includes parameter, B , needs be optimized, this can real results, modelling or judgement. Two important reference points equal 1 corresponds distribution approaching 0 log-normal results. Comparisons made with using other expressions where assumed Implementation approach demonstrated several examples from chemical analysis.