Edssential article from @headguruteacher :
As most people recognise, when evaluating the degree of success in a set of GCSE outcomes we need some sense of the baseline before we start making like-for-like comparisons. At the risk of stating the obvious, how well we’ve done all depends on what our results look like relative to the prior attainment of the students. This applies to comparing whole schools, year-on-year comparisons for one school, subjects within schools and teaching groups – especially if they are set by ability.
Given how long various data tools have existed and how commonly they are used, it still surprises me when school leaders, subject