If you read a headline that eating a bacon sandwich a day increases your risk of cancer by 20%, that’s sounds bad. Not according to Tim Harford, columnist of the Financial Times.
At a seminar of the Reuters Institute in Oxford, he gave a hair-raising account of the pitfalls awaiting journalists tempted to use juicy statistics in news stories.
So what cancer was involved? It turned out to be bowel cancer. How many people get bowel cancer in the UK? Four in 100. So a 20% increase means five in 100. Is that so much different? Is the bacon sandwich factor significant? Hardly.
A British Prime Minister announced that his government would spend £300 million over five years on care for pre-school children. Seemed a lot. But divided by five, the amount each year was £60 million. Around one million pre-school children in the UK qualified, so that made £60 per child per year. Which was about 20 pence per day.
“Not much childcare to be bought for that,” notes Harford.
These are his tips for journalists dealing with numbers:
- Is it true?
- What’s really being said? Does the statistic exactly define what’s measured?
- What’s the bigger story – the context, the history, the period of time?
Mmm. After 50 minutes of his harrowing tales, I think I’ll avoid numbers altogether. I’m just going to look silly.