Gerard Kelly makes a challenging, although not incontrovertible, argument for data as a necessary but not sufficient basis for making at least some educational decisions.

That argument is now part of the accepted wisdom in many jurisdictions. Yet there is a paradox as far as England is concerned. Here, the government’s obsession with performance data extends only to state schools. It is true that England’s education secretary, Michael Gove, cannot legally force private schools to collect performance data on their students’ progress before the age of 16. But nor does he even encourage them to subject their students to such testing. If performance data are so valuable, why exempt younger students in the private sector? Are private schools in other countries similarly exempt?

Colin Richards, Spark Bridge, Cumbria.