The benchmark figures on school attainment (621 census/survey observations) used are collected from census/survey information, as compiled by UNESCO, Eurostat, and other sources. The census/survey figures report the distribution of educational attainment in the population over age 15 by sex and by 5-year age group, for most cases, in seven categories: no formal education, incomplete primary, complete primary, lower secondary, upper secondary, incomplete and complete tertiary.

For total population aged 15 and over, 191 countries have at least 1 observation, and 112 countries have 3 or more observations. Most of our original data are from full censuses. These data points are used as benchmark figures on educational attainment. For the estimation of missing observations, we use enrolment rates and population by age group from the UIS database and UN population database, respectively. We have constructed complete estimates for the 146 countries.

Appendix Notes provide information on data sources for individual countries.