This dataset, a product of the Trade Team - Development Research Group, is part of a larger effort in the group to measure the extent of the brain drain as part of the International Migration and Development Program.  It measures international skilled migration, giving new estimates controlling for age of entry.

The methodology is explained in:
Beine, Michel, Frédéric Docquier and Hillel Rapoport (2006), Measuring international skilled migration: new estimates controlling for age of entry, Policy Research Discussion Paper, World Bank.

Definitions:

• Brain drain 0+: stock of skilled OECD foreign-born adults by country of origin as percent of skilled natives (i.e. emigrants + adult residents). This upper-bound measure is taken from Docquier and Marfouk (2006).
• Brain drain 12+: stock of skilled OECD foreign-born adults arrived in the destination country after age 12 as percent of skilled natives (i.e. emigrants arrived after age 12 + adult residents).
• Brain drain 18+: stock of skilled OECD foreign-born adults arrived in the destination country after age 18 as percent of skilled natives (i.e. emigrants arrived after age 18 + adult residents).
• Brain drain 22+: stock of skilled OECD foreign-born adults arrived in the destination country after age 22 as percent of skilled natives (i.e. emigrants arrived after age 22 + adult residents).

The "corrected" emigration rates are available for 192 origin countries, for 1990 and 2000.