Fitting the Statistical Distributions to the Daily Rainfall Amount in Peninsular Malaysia

Abstract. Daily rainfall data have been classified according to four rain types of sequence of wet days (Type 1,2,3 and 4). The Gamma, Weibull, Kappa and Mixed Exponential are the four distributions that have been tested to fit daily rainfall amount in Peninsular Malaysia. Parameters for each distribution were estimated using the maximum likelihood method. The selected model is chosen based on the minimum error produced by seven goodness of-fit (GOF) tests namely the median of absolute difference (MAD) between the empirical and hypothesized distributions, the traditional Empirical Distribution Function (EDF) Statistics which include Kolmogorov-Smirnov statistic D, Anderson Darling statistic A2 and Cramer-von-Mises statistic W2 and the new method of EDF Statistics based on likelihood ratio statistics. Based on these goodnessof-fit tests, the Mixed Exponential is found to be the most appropriate distribution for describing the daily rainfall amount in Peninsular Malaysia.