Dubious statistics
Journalists love to use single numbers, they do it all the time:
- Three British women will get pioneering womb transplants
- 4,000 foreign criminals including murderers and rapists we can’t throw out
- NHS hospitals save £400,000 by switching to same brand of surgical gloves
But single numbers are meaningless. People quote point metrics and statistics with abandon, but by definition, a single number doesn’t have any context. As single numbers don’t have any context they aren’t useful.
Adding context
There are three ways to add context to a point metric:
- Look at the history. How many women had new wombs last year?
- Find a comparator. How many criminals were home-grown? (Don’t forget the murderers and rapists.)
- Use a denominator. How many surgical gloves does the NHS use?
Better still do all 3. It is amazing what you can uncover with a few questions and a bit of logic.
The big fibbers
Big single numbers are the worst, the bigger the number the more impressive it sounds. Journalists know that if a number is so big it is difficult for us to get our minds around then we will automatically think it is important.
NHS could save £500 million a year by charging foreign nationals
There are so many questions:
- How much did the NHS spend on foreign nationals last year?
- How much do we spend on British nationals?
- How many foreign nationals are we talking about?
- What counts as “foreign”?
- How much do foreign health services spend on British nationals?
- What exactly do you mean by “could”?
In the overall scheme of things is that a big number? Or just one we aren’t used to?
It pays to be skeptical
Whenever somebody starts quoting single numbers at you (journalists, managers, doctors, lawyers, or politicians — especially politicians) ask for a comparator a numerator or the history. And don’t forget, the bigger and more impressive that number sounds the more suspicious you really ought to be.
Some numbers shouldn’t be trusted.
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James, this is one of my pet peeves about the media and when reports and presentations include numbers that are shown or discussed with no context. Makes no sense and is so misleading to not put this data into context.
Annette :-)