Graphical analysis was also done using the MATLAB fitting tool
graphical interface. Three different types of probability distribution
functions (normal, lognormal, and Weibull) were fitted to the data.
Figs. 4–6 show the fitted probability density functions, probability
cumulative functions, and probability plots, respectively. Comparing
the three different fitted functions, it can be concluded that the
normal andWeibull distributions fit the data with smaller error than
the lognormal distribution. As a result, the author chose to use the
normal distribution function since forecasting the cumulative probability
of the maximum annual rainfall result using the Normal and
Weibull distributions are very close.