Census: Costly but necessarry

From the Economist:
Censuses: Costing the count | The Economist

Costing the count

CENSUSES are as old as civilisation and governments are increasingly following the United Nations benchmark of tallying their people once a decade. Keiko Osaki-Tomita of the UN Statistical Division says that a record 70 territories are holding censuses in 2011. Only Iraq, Lebanon, Myanmar, Somalia, Uzbekistan and Western Sahara will fail to hold a count in this ten-year round.

The big growth in censuses is in Africa, but changes in the way they happen are coming from Europe. Fears of Germany’s anti-census lobby (which liked to chant “Only sheep let themselves be counted”) blocked counts for 24 years after 1987—a gap exceeded only by places such as Angola. Change came with a new European Union law requiring decennial headcounts. But the 80,000 census takers who were at work in May did not depend only on the house visits that privacy-conscious Germans find so troubling. Instead they culled data from national employment records and local population registers. Only around 10% of citizens were randomly selected for old-style surveys (with a stiff fine for those refusing to respond).

During this census round (which ends in 2014), 17 European countries will use government databases in some way. In nine, government-held data will be the only source of information.

Door-knocking is not just unpopular. It is costly. Finland, one of the first countries to ditch its shoe-leather census, saw expenses fall by more than 90% between 1980 and 1990, and now completes its counts for around €1m ($1.44m) for 5.3m people. America’s $13 billion census last year cost around $42 per head. Door-stepping is dangerous too. 15 census officials were killed during South Africa’s count in 2001.

Pete Benton, deputy director of the British census, says that using databases means that counts can be more frequent. That saves money too—gearing up once every ten years is expensive. And the long gap between traditional censuses is a growing problem as people become more mobile and households more flexible. Britain aims to decide by 2014 if it will bin the old methods for the 2021 census.

New approaches are harder for countries that do not keep a central population register. Continental European countries like Germany impose a legal duty on citizens to register their residence with the local authority. Others, like Britain or America, keep information in quite separate databases—dealing with, say tax, pensions, elections, passports, driving licences and health care. Some countries label their citizens with single identifying numbers. Elsewhere, that’s loathed. Even in well run Finland, the census-takers have to combine information from several dozen different data sets; efforts to link them started fully 50 years ago. High levels of immigration can also make government data unreliable, says Kevin Deardorff, of the American census office.

Modern-minded American statisticians also face thorny legal questions: the constitution calls for an “actual enumeration” of the population. That may make newfangled census methods vulnerable to challenges from the courts. A Supreme Court ruling already limits the use of statistical sampling, which adjusts survey data to include more accurately minorities, who are generally undercounted by older methods. In December the Government Accountability Office noted that the census’s cost has on average doubled each decade since 1970. Without “fundamental reforms”, the next one could cost $30 billion.

Yet recent censuses in Asia have proven that even the most mammoth old-fashioned headcounts can be done cheaply. In February India’s census authority completed a year-long effort of tallying and biometrically registering its 1.2 billion residents. The census part cost just over 40 US cents per head. In November China’s ten-day survey, carried out by 10m census workers, counted 1.34 billion people for what it said was the equivalent of $1 a time.

Governments rarely reckon that they need to know less. Indeed, says Mr Benton, “Sometimes the more information you have the more you want.” But how best to collect it? More data please.