Influenced by the perceived link between higher levels of educational attainment and growth, the education sector has seen significant reform efforts in recent years in a number of countries. Public spending in this sector has increased on average by one-fifth in real terms over the past decade and growth in terms of spending per student has also been marked in many countries (Figure 1, upper panel); governments in the OECD area now spend on average around 3% of GDP on primary and secondary education. However, a close correspondence between the level of resources and educational outcomes is difficult to demonstrate empirically: cross-sectional evidence reveals only a weak correlation between national spending per student or teaching resources and mean pupil performance in standardised tests (Figure 1, lower panels). Extra resources devoted to education do not automatically lead to commensurate improvements in outcomes.