This book cares about comparison between some classical and Robust methods to estimate model parameters for the analysis a Categorical data, based on the simulation procedure with application of real data to the best method was diagnosed by simulations. Categorical data found in applications studies as biological and medical. The book deals with the theoretical bases of the mentioned methods and the generation of data for the mathematical model with the addition of the case of contamination or outlier in the random error to demonstrate the efficiency method of fortification. Book included a set of subjects important for postgraduate students and researchers .