For the 20th anniversary edition of the Human Development Report in 2010, the Human Development Index (HDI) formula and key indicators were changed in several key respects to reflect changing development realities and greater global availability of data. The education component of the HDI is now based on two indicators: “expected years of schooling” for children now old enough to enter primary school, and “mean years of schooling,” representing educational attainment of the current adult population (ages 25 and up). Updated statistics in both categories will be used to compile the 2011 Human Development Index, which will be published in print and online in November in the 2011 Human Development Report.
The Human Development Report Office is publishing these newly updated national figures on mean years of schooling because they are not otherwise publicly available at this time; all other indicators used in the HDI can be obtained from the official public sources identified in our previously published material on HDI methodology: 
Technical notes [388 KB].
Mean years of schooling is a summary indicator usually estimated from census data and official demographic projections. The UNESCO Institute for Statistics estimates education attainment also from broad-based national surveys http://stats.uis.unesco.org/unesco/ . HDRO uses estimates based on the UNESCO’s compilation of data from censuses and surveys and the widely used Barro and Lee (2010) methodology for 143 countries http://www.nber.org/papers/w15902. Some estimates were updated in 2011 using newly available data, including education attainment distribution statistics from UNESCO. For other countries this indicator was estimated from international household surveys: the IFC Measure Demographic and Health Surveys (DHS) http://www.measuredhs.com, UNICEF Multiple Indicators Cluster Survey (MICS) http://www.unicef.org/statistics/index_24302.html , the World Bank’s International Income Distribution (IIDD) Database. In eight cases the estimate was derived from a cross-country regression (CCR) model.
In the table below the mean years of schooling are presented in 5-year intervals since 1980 for countries for which such estimation was possible. The column Sources/Method indicates if estimates are based on UNESCO data (UNESCO) or international surveys (DHS, MICS, IIDD). The methodology is denoted as either Barro-Lee (BL); Barro-Lee updated by HDRO (B-L, HDRO); or cross-country regression (CCR).
