“…So we estimated the bilateral inflows of immigrants by using two sets of explanatory variables: one set of variables explaining total immigration (both high and low skilled immigrants inflows), the other set explaining high skilled immigrants' inflows. In defining the set of variables explaining the overall bilateral migration flows (equation (2)) we use three main features in literature: (i) migration is positively correlated with bilateral aid (Berthelemy, Beuran and Maurel, 2009); (ii) migration is positively correlated with past immigrants settlements (Card, 2001;Beine, Docquier and Ozden, 2009); (iii) geographic variables are important to estimate bilateral migration flows (Mayda, 2008;Berthelemy, Beuran and Maurel, 2009; 21 Moreover the simple correlation index between per capita GDP and overall international aid by each destination countries is 0.196. Ortega and Peri, 2009).…”