Table 4 shows the mean values of bias, MAE and MSE of the relative frequencies of trees and the value of the Kolmogorov-Smirnov statistic (Dn) for the fits with both distributions of five tree species in forest stands in NW Spain. The observed and cumulative distributions fitted using the Gumbel and Weibull CDFs to describe extreme values of diameters in five species in northwest Spain are shown in Fig. 1. The mode method was not included in the maximum
diameter charts because of the poor results obtained with this approach.