Alongside the economical indicators (GDP) and Life Expectancy Index, it helps measure the educational attainment.
GNI (PPP) per capita and life expectancy are also used with the education index to get the HDI of each country.
Before 2010, the education index was measured by the adult literacy rate (with two-thirds weighting) and the combined primary, secondary, and tertiary gross enrollment ratio (with one-third weighting).
This means that a country whose citizens all attained 15 years of education by the age of 25, would have an MYS index of 1.0.
Worldwide education indexes are provided by the UNDP's Human Development Report derived from the UNESCO Institute for Statistics and other sources.