Plotting Position Formula From a Different Angle (PAP014747)

Código

PAP014747

Autores

Shizhong Lei

Tema

Floods in a changing climate

Resumo

Because of their importance in flood frequency analysis and flood risk assessment, plotting position formulas have been drawing tremendous attention over the past decades. Many modified versions of the Weibull formula, taking the general form of [Xi, (i+a)/(n+1-b)], have been proposed, where Xi is the i-th order quantity, n is the sample size, and a and b are some constants. Some researchers argue that only the original Hazen formula should be used since it is the only unbiased probability estimate for the order statistics. This paper proposes an approach to developing plotting position formulas that are population distribution dependent. By optimizing the plotting poison of the i-th order quantity, it's proven that for a given population distribution one may derive a plotting position that maintains the unbiasness of the probability estimate while having a much lower standard deviation than the Weibull estimate.