Statistics

Statistics about this sector circulate for years after they stop being true, usually because whoever repeated them did not link the source and nobody could check. You have probably quoted one in a grant application.

Every figure here names who produced it, what period it covers, and how large the sample was. Where a widely quoted number does not survive checking, the page says where it came from and why it is wrong, because that correction is often more useful to you than the statistic.

Original research will appear here as we produce it, with the underlying data published alongside.