CumFreq

The CumFreq model program calculates the cumulative (no exceedance, non-exceedance) frequency and it does probability distribution fitting of data series. CumFreq model program offers features such as various linear, logarithmic, exponential and double exponential cumulative frequency distributions, including the normal, log-normal (lognormal), (log)logistic, Cauchy, Pareto, Weibull, Frechet (Fisher-Tippett type II), and Gumbel probability distributions, and selects the best fitting distribution using the method of best fit.

The Cumfreq calculator model not only uses logarithmic but also exponential transformations of the data where the exponent (greater than 0) is optimized automatically and these so called generalized distributions have great flexibility, but they are mostly not used in other distribution fitting software.

CumFreq model program is also meant for segmented (in splines, piecewise) cumulative frequency analysis using a breakpoint which serves for example to study discontinuous probability distributions and return periods. It can analyze hydrologic factors like rainfall, river and drain discharge, water and river level.

CumFreq model program can also calculate the depth or level of watertable, soil salinity, and the hydraulic conductivity (i.e. soil permeability for water) can be sudied. The CumFreq calculator models the cumulative (non-exceedance) frequency distribution and fits it to a probability distribution where it also uses, amongst other, the normal, logistic, exponential and Gumbel distributions and also linearizes the probability distribution.

The software uses 20 different probability distributions and selects the best fitting. Preference for a certain distribution can also be expressed. An amplified version (CumFreqA), permitting to express preference for advanced composite distributions, can be made available on request.