Can statistics help catch terrorists?
Standing in a long queue at airport security with your fractious family, you might think it is pretty obvious you do not look like a terrorist. But is your journey through security about to get easier – and your flight safer? The government says it is considering screening passengers to decide which should undergo more rigorous security checks. But the practice, known as passenger profiling, is controversial. People behaving suspiciously or with an unusual travel pattern might find themselves under additional scrutiny but racial or religious factors could also soon form part of the criteria. But, in weighing up the merits of targeted versus random checks, the government will have to do its maths, because this seemingly straightforward idea is anything but in reality – not just because of fears that passengers will be unfairly discriminated against on grounds of ethnicity or religion, but because it involves some counter-intuitive number work. For a start, in relying on who your statist
