The Barro-Lee Data set extends our previous estimates from 1950 to 2010, and provide more, improved data disaggregated by sex and and by 5-year age intervals. It provides educational attainment data for 146 countries in 5-year intervals from 1950 to 2010. It also provides information about the distribution of educational attainment of the adult population over age 15 and over age 25 by sex at seven levels of schooling— no formal education, incomplete primary, complete primary, lower secondary, upper secondary, incomplete tertiary, and complete tertiary. Average years of schooling at all levels—primary, secondary, and tertiary—are also measured for each country and for regions in the world.

Aside from updating and expanding our previous estimates (1993, 1996, and 2001), we improve the accuracy of estimation in the current version by using more information and better methodology. To reduce measurement error, the new estimates are constructed using recently available census/survey observations from consistent census data, disaggregated by age group, and new estimates of mortality rate and completion rate by age and by education.