//-->
The Pre-programme Earnings Dip and the Determinants of Participation in a Social Programme. Implications for Simple Programme Evaluation Strategies.
Heckman, James J, (1999)
Removing the veil of ignorance in assessing the distributional impacts of social policies
Carneiro, Pedro, (2002)
The effect of schooling and ability on achievement test scores
Hansen, Karsten T, (2003)