Testing for sequential bias in school inspections

Inspectors are tasked with judging the quality of provision based on visits to schools. They conduct these inspections sequentially, completing one before moving on to the next. However, empirical research in a range of settings outside education suggest that prior judgements in a sequence can influence subsequent judgements, despite being logically irrelevant. We investigate whether school inspectors in England display such sequential bias by testing whether they judge similar schools differently, depending on the judgements they reached in prior inspections. We find only limited evidence of sequential bias in primary school inspections. In particular, an inspector reaching an ‘Inadequate’ judgement in their previous inspection is associated with a 42% reduction in the odds of reaching another ‘Inadequate’ judgement in their next inspection. Only around 5% of inspection judgements result in an ‘Inadequate’ and we do not find consistent evidence of sequential bias at other grades, meaning this bias only affects a small minority of judgements. We also do not find the same results for secondary schools, albeit in a much smaller sample.