  In the UK, US and elsewhere, school accountability systems increasingly
compare schools using value-added measures of school performance derived from
pupil scores in high-stakes standardised tests. Rather than naively comparing
school average scores, which largely reflect school intake differences in prior
attainment, these measures attempt to compare the average progress or
improvement pupils make during a year or phase of schooling. Schools, however,
also differ in terms of their pupil demographic and socioeconomic
characteristics and these also predict why some schools subsequently score
higher than others. Many therefore argue that value-added measures unadjusted
for pupil background are biased in favour of schools with more 'educationally
advantaged' intakes. But, others worry that adjusting for pupil background
entrenches socioeconomic inequities and excuses low performing schools. In this
article we explore these theoretical arguments and their practical importance
in the context of the 'Progress 8' secondary school accountability system in
England which has chosen to ignore pupil background. We reveal how the reported
low or high performance of many schools changes dramatically once adjustments
are made for pupil background and these changes also affect the reported
differential performances of region and of different school types. We conclude
that accountability systems which choose to ignore pupil background are likely
to reward and punish the wrong schools and this will likely have detrimental
effects on pupil learning. These findings, especially when coupled with more
general concerns surrounding high-stakes testing and school value-added models,
raise serious doubts about their use in school accountability systems.
