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The MC method is a powerful technique to establish a consistent link between theory and experiments. It helps to gain understanding of the transport properties and it provides macroscopic parameters which are necessary for the description of electronic devices. A single-particle MC technique is employed here to investigate stationary electron transport in GaN. The model includes the three lowest valleys of the conduction band. Several stochastic mechanisms such as acoustic phonon, polar optical phonon, inter-valley phonon, ionized impurity, and piezoelectric scattering are considered and their impact is assessed. The particular advantage of the MC method is that it provides a transport formulation on a microscopic level, limited only by the extent to which the underlying physics of the system is included. Since III-N material systems are yet not so well explored, several important input parameters are still missing or just inaccurately known. In an iterative approach the influence of the input parameters and their interdependence are assessed in order to get a set of parameters which are in agreement with experimental data available for different physical conditions (doping, temperature, field, etc.). Such a calibrated set of models and model parameters delivers valuable data for low-field mobility, velocity saturation, energy relaxation times, etc.