ABSTRACT
Value-added is a retrospective measure of school effectiveness based on the progress of students who have already moved on to a new Key Stage or who have left the school. It can never reflect the current impact of practice. It is also a relative measure of effectiveness since school-level CVA scores – the residuals from the model – and average performance are generated or redefined each year. It is not uncommon to hear all manner of stakeholders, from teachers to politicians, suggest that it is possible for all schools to be in the upper quartile performance band, or to question why such a high percentage of schools are below average! Value-added as a measure of school effectiveness is limited to ‘scholastic achievement’ (Mortimore 1998), but even within that it is limited to measuring school effectiveness by aggregating the value added for each student to a single score for the whole cohort. School-level scores therefore represent the value that the school adds for the average student, after adjusting for context. They are cross-sectional snapshots of the school since they only consider the progress made by a single cohort of students over a particular phase of their education,1 so that schools are only as good as their last set of data. This chapter addresses the issues raised by the aggregate nature of school-level scores and the restrictive snapshot view that value-added data provides.
