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Statistics schmanistics

October 30, 2011 Leave a comment Go to comments

Don’t you just love statistics? The security industry uses them extensively, but here’s a non-security example of why I love ‘em.

There’s a campaign here in the West Country to persuade all pensioners to retake their driving test, or at least take a refresher course. The argument is simple and an absolute clincher: one in five accidents are caused by pensioners.

But consider. Let’s say that pensioners are aged 65 to 80 (actually, here in the West Country they’re more likely to be 65 to 95 driving souped up Golfs). Anyway, 65 to 80 is fifteen years. The full driving span is 17 to 80; that is, 63 years; meaning that 48 years are occupied by pre-pensioners.

Now, according to the argument, one-fifth of accidents (20%) are caused by pensioners. So, in those 15 years, pensioners are responsible for a ratio of accidents to years (20/15); ie, 1.33. But pre-pensioners are responsible for a ratio of accidents to years (80/48); ie, 1.66. So, just on these figures, pre-pensioners are more likely to cause accidents than actual pensioners; and clearly it is we rather than they that need refresher courses.

The statisticians among us will say, whoa! you can’t prove that from those. You have an agenda, and you’re using statistics to prove it. But that’s my point. Statistics are never used for anything other than to justify a pre-determined course of action. Rightsholders twist piracy statistics to justify draconian copyright laws. Leftist governments twist economics to prove that we are better off under socialism. Rightist governments twist economics to prove that we need to do what is best for Big Business because it will benefit all of us (but them even more). All governments twist threat statistics to justify draconian anti-terrorist control laws. And of course some security companies twist cyberthreat statistics to persuade us to buy their product.

When offered statistical justification for something, bin the statistics. Base your course of action on your experience, your gut feeling, a pinch of logic and a dash of independent advice, and you’re more likely to choose the right course of action.

 

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