Opinion

Felix Salmon

When journalists forget they’re innumerate

By Felix Salmon
May 21, 2009

David Evans, the style guru for the Reuters commentary group, just sent out a note on numbers; its first paragraph should be seared into all journalists’ minds.

Always check any numbers in a story, and then recheck them. Are they internally consistent? If a number rises to a new number then is the second number larger than the first? Check that the units of measurement are not out by a factor of 10, or 100, or 1,000. Try to appreciate the underlying logic of the numbers rather than accepting them at face value. Ask yourself if the numbers are feasible and realistic. Remember that a journalist plus a calculator often equals mistake.

Journalistic innumeracy is a scourge of journalism for two reasons — firstly that journalists are innumerate, but more dangerously because journalists either forget or never knew in the first place that they are innumerate. It’s a form of overconfidence bias, and it’s highly corrosive. If we all try to remember every day that we’re all prone to making mistakes, especially when it comes to numbers, a huge number of boneheaded errors are likely to be avoided.

Comments
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Please remember to send that email to the Washington Post and the New York Times.

The housing bubble was only roughly $8,000,000,000,000 (trillion) — and the journalists at both of those papers decided to overlook the entire thing.

Include a link to Dean Baker’s Beat the Press blog.

Posted by Unsympathetic | Report as abusive
 

Paying copy editors more than $8/hour might help, too.

Posted by maynardGkeynes | Report as abusive
 

I believe “How to Lie with Statistics” is still in print. Could we take up a collection and send them all a copy?

 

I don’t think I’ve ever read a journalistic story in a newspaper that made statements quoting statistics that, upon reviewing the original sources, did not turn out to be more or less misleading.

Stylistic habits of mixing up the phrases when describing different proportions is often the culprit. Journalists will often write things like “A% was foo, while B% of the remainder was bar, and the rest were baz” – leaving you to wonder is that B% a percentage of (100 – A), or a percentage of the whole.

Just a couple of small tables of data would help hugely, particularly when percentages, ratios and proportions are being discussed.

Another bugaboo is people that talk about % differences but don’t mention the base rate – ignoring the fact that small bases can give rise to large but inconsequential percentages. Oh, and folks that talk about averages, but don’t mention variance or distribution shape – another black mark.

 

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