Following the data is all very well, but how should we decide which data to follow? Nate Silver argues that the total data are more important than the marginal data. There is more virus transmission in restaurants than in aeroplanes.The average Am…
The TotalData™ value chain is about the flow from raw data to business decisions (including evidence-based policy decisions).
In this post, I want to talk about an interesting example of a flawed data-driven policy. The UK Prime Minister, Theresa May, is determined to reduce the number of international students visiting the UK. This conflicts with the advice she is getting from nearly everyone, including her own ministers.
As @Skapinker explains in the Financial Times, there are a number of mis-steps in this case.
- Distorted data collection. Mrs May’s policy is supported by raw data indicating the number of students that return to their country of origin. These are estimated measurements, based on daytime and evening surveys taken at UK airports. Therefore students travelling on late-night flights to such countries as China, Nigeria, Hong Kong, Saudi Arabia and Singapore are systematically excluded from the data.
- Disputed data definition. Most British people do not regard international students as immigrants. But as May stubbornly repeated to a parliamentary committee in December 2016, she insists on using an international definition of migration, which includes any students that stay for more than 12 months.
- Conflating measurement with target. Mrs May told the committee that “the target figures are calculated from the overall migration figures, and students are in the overall migration figures because it is an international definition of migration”. But as Yvette Cooper pointed out “The figures are different from the target. … You choose what to target.”
- Refusal to correct baseline. Sometimes the easiest way to achieve a goal is to move the goalposts. Some people are quick to use this tactic, while others instinctively resist change. Mrs May is in the latter camp, and appears to regard any adjustment of the baseline as backsliding and morally suspect.
If you work with enterprise data, you may recognize these anti-patterns.
David Runciman, Do your homework (London Review of Books Vol. 39 No. 6, 16 March 2017)
Michael Skapinker, Theresa May’s clampdown on international students is a mystery (Financial Times, 15 March 2017)
International students and the net migration target: Should students be taken out? (Migration Observatory, 25 Jun 2015)
Oral evidence: The Prime Minister (House of Commons HC 833, 20 December 2016)
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