Pupils in every secondary school should be taught the statistical skills they
need to make sensible life decisions, one of Britain’s leading
mathematicians says.
A basic grasp of statistics and probability — “risk literacy” – is critical to
making choices about health, money and even education, yet it is largely
ignored by the national curriculum, according to the UK’s only Professor of
the Public Understanding of Risk.
David Spiegelhalter, of the University of Cambridge, told The Times
that as the internet transformed access to information, it was becoming more
important than ever to teach people how best to interpret data.
Familiarity with statistical thinking and the principles of risk could help
people to make sense of claims about health hazards and the merits of new
drugs, to invest money more wisely, and to choose their children’s schools.
Professor Spiegelhalter has developed programmes for teaching risk literacy,
based on familiar subjects such as the National Lottery and football league
tables, which his team is introducing to schools through a “Risk Roadshow”.
He believes that something similar should be offered as a matter of course.
“I regard myself as part of a movement we call risk literacy,” Professor
Spiegelhalter told The Times. “It should be a basic component of
discussion about issues in media, politics and in schools.
“We should essentially be teaching the ability to deconstruct the latest media
story about a cancer risk or a wonder drug, so people can work out what it
means. Really, that should be part of everyone’s language.”
As an aspect of science, risk was “as important as learning about DNA, maybe
even more important,” he said. “The only problem is putting it on the
curriculum: that can be the kiss of death. At the moment we can do it as
part of maths outreach, maths inspiration, which is a real privilege because
we can make it fun. It’s not teaching to an exam. But I actually think it
should be in there, partly to make the curriculum more interesting.”
Risk literacy could be taught as part of maths, science, or civics and
personal and social education, Professor Spiegelhalter said.
His tools include an animation of National Lottery results. While every number
has an equal probability of being drawn every week, some have come up much
more often than others, through chance alone.
“Number 38 has come out 50 per cent more often than 13, and 38’s been in the
lead since about 2000. But that’s so uninteresting: there had to be a number
at the top and one at the bottom, and they just happen to be 38 and 13. It’s
a great tool for teaching people about chance.”
Such simple examples can be used to explain more complex statistical
principles, such as recognising that apparently improbable occurrences are
often in fact predictable in a population as large as Britain’s.
“You can tick off story after story that’s probably interesting to the people
it happened to, but not statistically unusual at all. There was a recent
story about a family in Gloucestershire with three children all born on
January 29. We were contacted by a journalist and asked what are the chances
of this happening.
“The chances are about one in 135,000, or seven in a million. But there are a
million families with three children in the UK. So it’s almost certain that
this family is not unique and when the story went online, someone wrote in
and said, ‘I was born on the same day as my two brothers’.”
A big problem with the public’s understanding of risk and statistics was that
the human mind seemed to be evolved to see individual stories as more
significant than they really were.
“We seem to grossly overinterpret immediate stories that happen to individuals
around you, and from an evolutionary point of view that might be enormously
valuable,” Professor Spiegelhalter said. “It’s better to run away from a
predator, even if you’re mistaken. It’s very difficult to think calmly about
uncertainty. That’s why it needs to be taught.”
The unfounded scare over the MMR vaccine, and outlandish claims of success for
alternative medicines, were prime examples.“One must think all the time of
what is not being reported – the dog that didn’t bark. When we see a
hole-in-one video on YouTube we are sensible enough to know that this has
been selected out of millions of shots that missed. We need to think the
same way every time we hear of someone claiming that some new treatment has
cured them.”
People needed tools to assess the morass of information about health and other
matters that was now available, and statistics could help, he said. “The
ability to find information on the internet is increasing, the availability
of information is increasing all the time. At the same time, what’s also
increasing are the number of people trying to manipulate opinion using
‘sciency’ arguments. It’s very important people understand how evidence is
used, variability and uncertainty and so on.”
It was also important to know what sort of statistics to seek out for your
purpose, Professor Spiegelhalter said, citing school league tables as an
example. These had two different objectives, to help parents to choose
schools and to hold schools to account, and the data that best suited each
purpose were different.
“If you want to hold a school to account, it’s quite reasonable to allow for
the neighbourhood in which it operates,” he said. “So if it’s in a very
deprived neighbourhood, you should be comparing them with other deprived
schools and adjusting for deprivation. A school might be doing a very good
job if it’s getting 40 per cent GCSEs. That’s accountability.
“But if you’re choosing a school for your child, you don’t have to take
account of deprivation. In fact that’s completely irrelevant. You choose a
school that will be best for your child.”
Reality check
Professor Spiegelhalter’s four rules of risk, which he says everyone should
know
Stuff happens We cannot predict exactly how every precise event will
turn out, but we can often predict the overall pattern of events
surprisingly well
Compare like with like If you want to show that speed cameras reduce
road traffic accident rates, don’t just put them in places that have just
had a run of accidents
What am I not being told? This person may well have got better after
she took this wonder treatment, but how many other people’s stories are not
being featured?
Twice not-very-much is still not very much Increasing a tiny risk may
not be so important: almost everything interesting might help and it might
also harm. The trick is working out the balance for you
