Road traffic casulaties are under-reported, says the Statistics Authority in a new assessment of the data collected by police officers and reported by the Department for Transport.

Deaths are accurately counted, but many injuries slip through unrecorded. In future, the release of the data should be accompanied by an estimate of just how great the undercounting is, if they are to meet the Code of Practice and continue to be recognised as National Statistics. In addition, the department needs to think about spending more money gathering the data, and police officers are urged to try harder to record all injuries.

The assessment is one of six in the ongoing and Herculean task the authority has set itself of reviewing all sources of national statistics. The other five cover migration, road freight, energy, overseas aid and future prison populations.

All get a relatively clean bill of health except for our old friend the migration statistics ("not fit for purpose"). Internal migration, roughly guessed on the basis of GP registrations, is especially weak.

And, in a recommendation the Ministry of Justice may not especially welcome, future estimates of prison populations should be accompanied by figures of the actual number of prison places, to enable users to work out just how overcrowded the jails are going to be. Full access to all six reports is available here.