Screenshot of BBC expenses claims
Anyone who has observed a journalist feverishly working on their expenses claim, calculator in hand, swamped by coffee-stained receipts, will scoff at suggestions that members of the news media are mathematically-challenged.

The level of maths skills - not to mention fantasy - involved in filling out an expenses form puts most rocket scientists to shame.

Added to which, recent stories about MPs' spending habits, plus the credit crunch, have all required a degree of competence when it comes to writing about figures and statistics.

But still the myth endures that journalists and numbers are an explosive mixture best kept apart.

Now this isn't a myth to which I subscribe. Not only do I find that the journalism students with whom I work are generally comfortable and confident with figures, but no working journalist can afford to be numerically illiterate, any more than he or she can afford to write sloppy, grammatically incorrect prose.

That's because journalists have to be able to challenge the information presented to them and to present it in a way that readers can readily understand.

Often, that information involves or is based around numbers - whether it be a story about an election, a budget, the economy or an MP's claim for their second home.

It doesn't require a higher degree in calculus to work with numbers, but it does require applying common sense and the same critical thinking that goes into any other news story.

Example 1
You receive a press release from a local action group. It tells you that a village in your patch has the highest number of hit-and-runs in the county at 52, so you rush to write about the region's most dangerous drivers... until you're brought short by the newsdesk.

How many people live in the village? Erm, 5,500. Did you notice that the press release mentions a neighbouring village (pop. 1,250) which had 44 hit-and-runs in the same period? So although the number was higher in your village, the rate was nearly four times higher in the neighbouring village - 0.035 as opposed to 0.01. Which is the more dangerous now?
Ok, so that's an artificial example, but the problem of confusing quantity with rate is a common one. In order to compare the likelihood of events in different localities, you should always look at the number of times that event has happened (the quantity) divided by the number of people the event could have happened to (the population).
But when we write up the story, we want to present the numbers in a more intuitive way. Not only is the rate of 0.01 quite inelegant, it's also only an approximation to the true figure of 0.009-and-a-bit. A better way of expressing the rate would be as 'about nine people in a thousand'. The rate for Village 2 is about 35 people in a thousand. This way of expressing the numbers also makes it easier for readers to compare them.

Of course, such a story about rates should also give some context - has the rate for Village 2 changed much over the past 10 years? What appeared a drop in the 1990s to 22 hit-and-runs merely reflected the smaller population in that period (625), so that the rate is exactly the same.

Example 2
In addition to rates and percentages, the other common pitfall for reporters is averages. Most journalists do seem aware that there is more than one sort of average, although they can be a little fuzzy on what exactly these are.

The important point is to be wary of any report or press release quoting 'average' figures - as well as 'average' having at least three distinct definitions, the cunning selection of timeframes and of what to compare can completely distort the true picture.

'Average house prices fall 15 per cent' - not only do I want to know which average you're using, but also what time periods you are using, which parts of the country and what housing stock, as well as the source for the underlying figures.

By choosing a different average and varying the timeframe, it's quite possible to show average house prices have actually risen 15 per cent.

Don't be suckered by the lazy option - always challenge the use of averages until you know what it includes, and (just as importantly) what it excludes.

Now nothing above is exactly mentally challenging. It is a question of deciding what questions to ask of the numbers, and how to report the answers. Fundamentally, it is no different from any other type of story.

There can be no excuses for reporters failing to get to grips with figures. Training and education can help the new generation of journalists to ward off the fear factor, but nothing beats the age-old combination of curiosity, accuracy and credibility.

Read part two of 'How to: get to grips with numbers as a journalist'.

Steve Harrison is a journalism lecturer at Liverpool John Moores University, having spent most of his working life as a journalist with the Liverpool Daily Post and Echo.
An Oxford graduate in English, Harrison began his career at the Winsford Guardian in 1983 before moving to the Post and Echo in 1986, where he was variously a reporter, sub-editor and online editor. His last role there was as acting assistant editor (digital), responsible for running the websites of both the daily titles.
He also has an interest in newsroom numeracy - so much so, that he is due to complete a BSc in Mathematics with the Open University later this year.
He blogs on the subject at Newsroom Numeracy.

See also: Meet the Trainers: Stephen Kahn - How to get a head start as a financial journalist

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