How data is aggegated, protected and surfaced

Every “national” figure here is drawn from the schools that use Arbor and share data, not from every school in England. Because that sample is large and spread across regions, phases and local authorities, it is a statistically meaningful indicator of the national picture — but it is Arbor's data, not an official DfE or census statistic, and it may differ from published national figures. For that reason we report findings as percentages, rates and proportions (for example share of pupils on roll, or attendance rate) rather than raw counts: proportions stay comparable and representative even though Arbor covers part, not all, of the country. Absolute counts describe Arbor schools specifically, not the whole of England.