Covid-19 has put the power and accuracy of statistics at centre stage. Infection rates, 'R' numbers, new cases, hospital admissions and the data underpinning new vaccines are being used by the media to tell stories about the pandemic, and are scrutinised daily to make vital public health decisions.
It is familiar territory for 'undercover economist', journalist and broadcaster Tim Harford who explores the beauty of statistics, and their uses, abuses and shortcomings in his new book How to Make the World Add Up.
The book is Harford's eighth following his bestseller The Undercover Economist, and the popular book (and BBC podcast) 50 Things that Made the Modern Economy.
Hartford told Kim Hill he knows only too well how a mistake using a false number can have consequences.
Late this summer in the UK he wrote a piece for the Financial Times which went viral.
It was to help a friend of his aged 60 determine what his risk was of catching a fatal case of Covid was.
“I did all the numbers, back then there wasn’t much virus around in the UK, sadly there’s a lot of it around now, back then I reckoned he had a one in 2 million chance of catching a fatal case of Covid.”
The same chance of dying in a bath or from riding a horse, he says.
But he got one number wrong, the one about the risk of dying in a bath.
“I think it is the is the most famous thing I’ve ever said, because it’s the most interesting thing I’ve ever said and it’s the most interesting thing I’ve ever said because it turns out it’s wrong.
"It is a warning. A lot of what we see we see because it’s interesting, and a lot of stuff that’s interesting is interesting and surprising because it isn’t right.
“People got bad information from me, and they got it magnified much more than my apology or retraction could ever attract attention to.”
He has 10 rules for thinking differently about numbers.
The first is notice your own feelings, he says.
“So much of what we see we accept or reject very, very quickly and we do so because of our own pre-conceptions.”
Take a moment and reflect before retweeting or sharing a piece of information he says.
Statistics can be manipulated, but assuming they are all wrong is a dangerous mind set, he says.
“Statistics are a vital tool for illuminating the world around us. There are things that we can’t see in any other way, we have to have statistics.
It’s like a telescope for an astronomer, or radar for air traffic control and if we get too obsessed with spotting the tricks and spotting the lies we can take ourselves to a very dark and quite corrosive place.”