"There is substantial cross-country variation in secondary school design, with some countries tracking students into different ability schools very early, and other countries with little or no tracking at all. Does tracking length affects school performance, as measured by standardized test...

"It is difficult to know whether widening access to schools which provide a more academically oriented general education makes a difference to average educational achievement. We make use of reforms affecting admission to the 'high ability' track in Northern Ireland, but not England. The...