I distrust statistics because:

• they are often inaccurate
• you can always doubt whether they measure what they purport to measure
• you can always question whether the thing they are measuring is good or bad
• you can lie with them

Inaccurate?

A good friend of mine always gave the example of lung cancer statistics.  According to her lung cancer is very difficult to diagnose.  It is even more difficult to identify as a cause of death.  Sure you can cut up the corpse but that doesn’t usually happen.  Doctors have to guess and if they know that the deceased was a smoker they’ll tend to put down lung cancer as the cause, so re-inforcing the link.

I can probably come up with a better example than this but this will have to do for now.

I am going to start compiling a list.  Here’s a fairly minor example: SATs fiddled.

Not measuring what they purport to measure?

A favourite example of mine is the rail passenger statistics.  Every year the government publishes some stat saying X billion passenger miles were covered.  But how would they know?  They’re not following us about - at least not yet.  All they can really go on is what tickets are sold and take an estimate from that.  But some people dodge the fare.  And some people cancel their journeys.

Good or bad?

Using the example of passenger statistics again, after privatisation, every year the passenger-mile numbers went up.  This was hailed as a good thing but for whom?  If you were one of those being crushed in an overcrowded carriage you might well have rathered that the numbers went down.  Sure, there’s an argument that global-warming-speaking rail travel is better than road travel - though by no means an open and shut one - but presumably other forms of travel or no travel are even better.  If the numbers are made up from people who would otherwise have stayed at home it is not necessarily a good thing.

Lying?

There’s a book out there called “How to lie with statistics”.  I’ve never read it myself but I can imagine the sort of thing it goes into.  Statements like “up to”, and “as many as” are tell-tale signs that you are being lied to.

Permalink • General • Last Updated: 08 November 2006

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