Abstract:
Sample selection models or selectivity models are often used to analyse structural and evaluation studies. Everywhere, individuals who are selected into one group, will likely be different from the characteristics of individuals in other groups. This selection problem is the core problem that must be considered. As this selection process occurs, this is a very important factor to be observed. Ignoring the non-random selection will lead to selection bias, either on the basis of observed or unobservable characteristics which will be the focus of this study.
