A Polychotomously- Scored Responses Model and Parameter Estimation

In this paper, we adopt non-linear least square method to estimate the polychotomouslyscored items and examinees’ ability parameters of the polychotomously-scored responses model. We illustrate the rationality of the parameter estimation of this model. We apply the model to chotomously-scored items and compare the result of non-linear least square method to that of linear least square method.