Global Estimates of Mean Years of Schooling: A New Methodology

The indicator of mean years of schooling (MYS) has the advantage of expressing the distribution of educational attainment in a single number. It is often used for cross-country comparisons and in economic and environmental models as the unique indicator of educational attainment and human capital stock. The computation of MYS from a given educational attainment distribution is complex for two main reasons. First, the standard duration of different levels of schooling varies from country to country, and within countries each school level can have different lengths depending on the type of studies, for example, studies of general secondary as opposed to vocational secondary. Secondly, the calculation is biased by the presence of pupils/students who do not complete the full course at any level, which can amount to a substantial share in some countries. To overcome these difficulties, the methodology used and detailed in this paper computes MYS as the weighted mean of six educational levels based on ISCED 1997 classification - no formal education, incomplete primary, completed primary, completed lower secondary, upper secondary and post-secondary education . and the procedure takes into account country-specific educational systems as well as changes in these systems over time. To adjust for the proportion with incomplete educational levels, we developed regional sets of regression models to improve estimates of MYS for the incomplete primary category and a set of correction factors to adjust higher levels. The models are built using detailed data on duration of schooling by grades completed within primary level for 54 countries. We apply the method to estimate MYS for 171 countries in the Wittgenstein Centre (WIC) dataset on educational attainment, which served as the base for the population projections by levels of education until 2100. Detailed data are available online at www.wittgensteincentre.org/dataexplorer. In the paper we compare our method and results for 2010 to the widely used Barro & Lee data and to that of UNESCO, the main provider of global data on education statistics, and explain the differences