One question I get asked a lot is: “You say that Frewmanackshire is a terrible local authority. How do you know? Do you know what we are working with?” etc etc. It is true that schools with radically different intakes cannot be usefully compared. So I thought I would let you in on how I benchmark schools, and supply you with two jolly new maps.
What I do for secondary schools, is run a simple regression – that is to say, I fit a simple line through all the pupils’ school results in the country after asking it to account for the children’s ethnicity, poverty and prior test results. Unlike other models, the regression contains precisely zero information about the schools – only data about the children.