I am using Matlab 2012a to run those 3 tests. When i run with my data, all the time I obtain very small values and for the AD tests, the results are not even normalized. please verify my code. I am also using the A-D script which is found at this link [enter link description here][1] sample= N; h1=histfit(sample,30,'weibull'); xdata1 = get(h1(2), 'XData'); ydata1 = get(h1(2), 'YData'); [~,p_weibull_cs,stats_weibull_cs] = chi2gof(ydata1); [~,p_weibull_ks,stats_weibull_ks] = kstest(ydata1); p_weibull_ad = AnDartest(ydata1); [1]: http://www.mathworks.com/matlabcentral/fileexchange/14807-andartest