The Association of School and College Leaders analysed the 1,011 school inspections carried out in 2005-6. Some 88% of schools given Ofsted's top leadership and management rating had pupils with average or above average attainment on entry, the union said.
Only 7% of schools in deprived areas with low attainment got the same grade. This was because an "apparent bias" gave schools in affluent areas a "built-in advantage", the union argued.
It said the most immediately striking feature arising from the data was the type of schools where outstanding leadership and management were identified.
Related articles:
