Maybe There Will be a 2021 Census in the UK After all

More than three years ago, I commented on an article in the Economist discussing the UK government's  consideration of replacing the 2021 census with data from administrative sources, largely as a way of saving money. At the time, the Economist seemed generally to be in favor of such a move. This week they came to their senses, as it appears to them that the government is unlikely to abandon the census.

EVERY ten years since 1801 the British government has conducted a census, counting every man, woman and child. Is this elaborate and costly exercise still necessary? The most recent census, conducted in 2011, cost £480m ($770m)—a 35% increase in real terms over the 2001 census. On September 23rd the Office for National Statistics (ONS) began a three-month public consultation to evaluate two new ways to count the population. 

Unlike surveys based on random sampling, the census provides extremely accurate and fine-grained data. Researchers can look up the results for a single street. Counting everybody is also the most reliable way to determine the size of the total population: the 2011 census revealed that there were 500,000 more people in England and Wales than statisticians had thought. But this accuracy is expensive and short-lived.

The ONS proposes two alternatives. The first option is to conduct the census as normal every ten years, but to collect the bulk of responses online. When the ONS offered the option to respond online in 2011, 16% of households took it up. This would preserve the detail and accuracy of the traditional census, and at £625m would cost less than another paper-based census (estimated to cost £800m). But the information gathered would still go out of date just as quickly.

Canada has been successful with online responses and it would probably work in the US as well, but so far it is has not been tried. It seems likely, as the Economist notes, that the online option will win out, saving money and allowing the census to move forward. If the UK is smart, they will also move to a continuous survey like the American Community Survey to keep the data updated between the complete counts.