Comparison of estimation methods for fitting weibull distribution to the natural stand of Oluwa Forest Reserve, Ondo State, Nigeria
The relative performance of any distribution function truly depends on the estimation methods and where this is wrongly chosen poor fit is inevitable. This may mislead forest managers and thus thwart effort towards sustainable forest management. This study therefore compared estimation methods for fitting 3-parameter Weibull distribution to the natural stand of Oluwa Forest Reserve, Ondo State, Nigeria with a view to enhancing sustainable management of the tree resources. Systematic sampling technique was used in the laying of eight (8) temporary sample plots (TSPs) of size 50m x 50m in the natural forest. Three fitting methods were used that based on maximum likelihood, moments and percentile. Comparison was based on Kolmogorov-Smirnov statistic (K-S), bias, mean absolute error (MAE) and mean square error (MSE). The result revealed that maximum likelihood method was more accurate in fitting the Weibull distribution to the natural stand. It had the smallest mean bias and MSE values of 0.00009 and 0.00021, respectively. Maximum likelihood method is therefore recommended for fitting the 3-parameter Weibull distribution to natural stand of the reserve.
Keywords: Weibull distribution, maximum likelihood, moments, percentile, natural stand