Tuesday, January 21, 2020

census big data

Is there a better way? For the first time this year, Americans will be able to fill out the census online. This risks missing hard-to-reach groups such as indigenous populations and the old. It also introduces unforeseen headaches. In 2016 Australia’s census website crashed, leaving millions unable to submit their responses and venting their anger with the hashtag #censusfail.
Nordic countries have ditched the unwieldy undertaking altogether, turning to other sources of information. In Sweden each citizen is given a personnummer, an identity number linked to government data on individuals’ health, employment, residence and more. These data are cross-referenced to produce statistics resembling the results of a traditional census. Denmark, Finland and Norway take the same approach. As societies share more information, wittingly or otherwise, new statistics can be produced. Mobile-phone records, for example, have been used to estimate commuting patterns. The Netherlands, meanwhile, conducts what it calls a “virtual” census. This is similar to the Nordic model, but also uses small-sample surveys to produce data not already held by the state, such as education levels and occupation.
As long as each citizen has a unique identifier, such counts are cheaper to carry out—the Dutch government boasts that its census in 2011 cost just $0.10 per person—and can be done much more regularly. But the accuracy of the data is harder to guarantee. Population registers are never completely up to date and anyone not already on them will be missed. In Europe, two-thirds of countries are expected to use data from existing registers to some extent in the next round of censuses. This is up from just a quarter 20 years ago, according to analysis by Paolo Valente, a statistician at the UN.
Making such a change is a slow process. Bernard Baffour, a researcher at the Australian National University, points out that it took decades for Sweden to implement a fully register-based census, partly because Swedes had to be reassured that their data were secure. As he puts it, “When a doctor asks how much you drink or smoke, are you happy for that to be linked with all the other information on you?” Frank de Zwart, a professor at Leiden University in the Netherlands, also criticises register-based censuses for neglecting a key political function of censuses. For minorities such as native Americans, filling out a census is a powerful assertion of their place in society. A virtual census would deny them this opportunity. That said, self-reporting is far from perfect: 177,000 Britons implausibly claimed to be Jedi knights in the census of 2011.
Even though Britain does not have identity cards, common in the rest of Europe, in 2013 the government tried to replace the census with other administrative data it already held. An outcry from MPs and statisticians forced ministers to shelve the idea. The public had rejected an attempt in 2006 to introduce identity cards, and recent scandals such as the harvesting of personal data from Facebook deepened Britons’ worries about privacy. Iain Bell, the statistician in charge of the census at the Office for National Statistics (ONS), emphasises the importance of public trust in producing official figures: “If people don’t want a single register of the population, we have to respect that and look to other sources.” Francis Maude, then a government minister, told MPs in 2014 that he hoped the next census, due to take place next year, would be the last. In 2023, the ONS will report back on whether this is achievable.
Political rows over America’s census have shone a light on a function of government that most people consider only a handful of times over their lives, but the results of which affect them every day. Recording each member of every household seems outdated in the age of big data, whether the data are held by governments or private companies. But in this sense, at least, America’s federal government is not big enough; its social-security system is too incomplete, and other information still too patchy, to replace the old-fashioned head-count. Will Mr Dillingham be the last enumerator to visit Toksook Bay? Don’t count on it.

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