PARENTS pore over them. Teachers protest about them. Politicians preen when they are positive—and blame their predecessors if they are not. International league tables have acquired a central role in debates about education policy.
Data duels are a recent phenomenon. The OECD (a Paris-based developed-country think-tank) has published its PISA (Programme for International Student Assessment) studies of 15-year-olds’ proficiency in reading, maths and science every three years since 1997. TIMSS (Trends in International Mathematics and Science Study) has conducted four-yearly assessments of attainment at nine and 13 years of age since 1995. In 2011 it coincided with the quinquennial PIRLS (Progress in International Reading Literacy Study) which has