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Introduction screen to CumFreq program (model).
The CumFreq calculator models the cumulative (nonexceedance) frequency distribution and fits it to a probability distribution. It uses, amongst other, the normal, logistic, exponential and Gumbel distributions. For distribution fitting, the CumFreq software app linearizes the probability distribution.For a list of linearizations, based on logarithmic and other transformations, see: transformations 
Input tabsheet
The input tabsheet shows the probability distributions that are being used in the CumFreq software model to fit the data to. In this application program one can select "best of all" or indicate a preference. The number of intervals needed to prepare the histogram can be entered. 
Cumulative distribution fitting
Probability distribution fitting is based on plotting positions (the observed data). A 90% confidence interval of the fitted probability distribution is shown. It is a specialty of the CumFreq software model calculator to apply "generalized" distributions, which, in this application program, makes them fit better than the standard ones. They are based an an exponential transformation of the data to obtain a closer fit. 
Histogram of fitted distribution
The histogram provides the observed and calculated frequencies by interval. The histogram gives an impression of the symmetry of the probability distribution and whether is skew to the left or to the right. 