Which HDI sub-index combines mean years of schooling for adults and expected years of schooling for children?

• A. Life expectancy index
• B. GNI per capita (PPP)
• C. Line of perfect equality
• D. Education index

Answer: (D)

The Education index is the HDI sub-index that blends the two schooling indicators. It combines mean years of schooling for adults with expected years of schooling for children by normalizing each measure to a 0–1 scale and then averaging them. This creates a single number that reflects both how much schooling people have already completed and how much schooling children are expected to receive, capturing both current attainment and future educational potential. The other sub-indices focus on health (life expectancy) or income (GNI per capita PPP), and there isn’t a HDI sub-index called a line of perfect equality.