Armchairs, When you try to measure returns to schooling in a cross section of countries, how do you account for the fact that school coverage varies from place to place? --ie, the percentage of population attending basic school varying from place to place... Is there a direct relationship between the share of population attending school and the distribution of skills within that population sample? --I woud think that if 10% of a given country population attends high-school, their skills' distribution will probably be different from one where 60 % does so...