Self-selection and the performance of return migrants

"In this paper, using the framework of a Roy theoretical model, we examine the performance of return migrants in Albania. We ask two main questions: (i) Had they chosen not to migrate, what would be the performance of return migrants compared to the non-migrants? and (ii) What would be the performance of non-migrants had they decided to migrate and return? Both our estimates from a selection model and our semi-parametric approach allow us to conclude that the flows of return migrants are negatively selected. We find that, had they decided to migrate and come back, the non-migrants would have earned more than twice the wages of return migrants"--London School of Economics web site.