WHEN the first results of the 2011 census were published, almost two years ago, the moststriking discovery was straightforward. Britain's population, it turned out, was around500,000 bigger than statisticians had thought. For all that Britons are relentlessly surveyed,only a full count could reveal the size of the country, yet alone that of individual cities, townsand neighbourhoods.
Given that finding, the proposal made in 2010 by an austerity-minded coalition government toscrap Britain's decennial census seemed odd. It now looks as though the census will surviveafter all. On March 27th the Office for National Statistics (ONS) concluded that a full populationcount is still necessary, though many people will in future be asked to fill in the census online.In all likelihood, the government will follow its recommendations. Academics, marketresearchers and social historians breathed a sigh of relief.
Scrapping the census in favour of rolling surveys of a portion of the population was always asilly idea. A full count can provide information at the level of a single street, which even verylarge surveys could never do. The census also supplies detailed data about poorly understoodgroups of people, such as some ethnic minorities. Each year billions of pounds of governmentspending are allocated according to estimates derived from the census. Its data determinewhere new schools and hospitals are built, where planning permission for housing is grantedand where money is spent on transport.
The census is hardly perfect. It is expensive—the 2011 edition cost around 480m (800m). Itsfindings go out of date quickly. And it is increasingly difficult to conduct, as a rising proportionof people do not fill in their forms. In many European countries, including Germany and theNetherlands, the authorities use administrative data collected by public bodies in place of atraditional census.
In Britain that would be tricky. The nation lacks a central population register or an identity-card system that would allow administrative data to be linked up. By northern Europeanstandards, Britain also has lots of irregular migrants who have little interaction with the state.That makes a full count unavoidable. Yet the authorities should still be investing in working outhow to use administrative data better, argues Chris Skinner, a statistician at the London Schoolof Economics. That would help to provide a check on the accuracy of census and surveydata, as well as providing timelier and more precise estimates in between census years.
The ONS agrees—and it is researching the possibility of using government data better. Thetrouble is that doing so will mean spending money, which is precisely what ministers wanted tostop doing when they pushed the ONS into thinking about cancelling the census. Data userswill be hoping that they have a change of heart. If not, Britain might be stuck with inadequatenumbers for decades to come.