This morning, the UK’s Shadow Public Health Minister Luciana Berger did an interview on the BBC’s Today Programme in which she argued that smoking should be banned in cars where children are present because we know:
“A single cigarette can create concentrations of tobacco smoke in a car that is 23 times more toxic than in a typical house.”
The interview (which you can listen to here for the next 7 days) and figure Ms Berger quoted have been picked up almost verbatim by the mainstream media including The Mail, The Daily Telegraph and The Independent.
As someone who does a lot of work on risk communication, I was immediately struck by the 23x figure, partly because of its numerical value and partly because of the visual picture it conjured up of smoky cars and houses.
When humans assess a new risk the brain initially does so by generating images (also known as mental models). This goes some way to explaining why some experts or campaigners are better at explaining risks than others. Numbers are important as proof – but numbers which create pictures or explain relationships are even better because they allow the bit of the brain that deals with risk to process them more meaningfully. This is something that scientists or other ‘rational’, evidence-based professions often overlook when talking about the risk posed by issues as diverse as fracking, GM or chemicals.
But it’s a lesson that can equally apply to other number-heavy professions when preparing experts for interview. Ms Berger only used two figures in her interview (the other was 500,000 children a week) but they were simple, meaningful and clear.
Picking a few clear numbers and taking the time to put them in context is a far better use of interview preparation time than digging out 20. I have no idea where Ms Berger got her figures (nor am I implying that they aren’t true). But clearly, they made enough of an impact on the mainstream press who picked them up unchallenged thus ensuring even more free PR for the policy and presumably more exposure for Ms Berger.
A good number counts for a lot with journalists: and some might say its value can’t be measured.