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1st November 2020

Imagine for a moment that, for reasons too convoluted to go into, you find yourself a contestant on a 60’s US TV game show. Given a choice of three doors, behind one a car; behind the others, goats, you chose door 1. The host, who knows what’s behind them, shows you a goat behind door 3 and offers you the chance to change to door 2. What, assuming you’d prefer a car to a goat, should you do? 

The correct response, as every good skeptic knows, is to brick up the doors, preferably with the host behind, walk away and never speak of this again. The only other alternative being a statistical mindfudge best avoided. Unfortunately, not all problems are so easily solved and, as we’re seeing in these difficult times, a good understanding of the statistics can contribute enormously to making the world add up.

So it is that Skeptics in the Pub – Online offers a timely welcome to Undercover Economist and host of BBC Radio 4’s More or Less podcast Tim Harford, who hopes to help us overcome our hesitancy and distrust of statistics with his ten simple rules for thinking differently about numbers. Although, in a typical piece of statistical mindfudgery, there are, of course, eleven of them. Next slide, please.

Cambridge Skeptics

How to Make the World Add Up:
Ten Rules for Thinking Differently About Numbers
with Tim Harford
Thursday, 5th November 2020 at 7:00pm
When was the last time you read a grand statement, accompanied by a large number, and wondered whether it could really be true? Statistics are vital in helping us tell stories – we see them in the papers, on social media, and we hear them used in everyday conversation – and yet we doubt them more than ever.

But numbers – in the right hands – have the power to change the world for the better. Contrary to popular belief, good statistics are not a trick, although they are a kind of magic. Good statistics are not smoke and mirrors; in fact, they help us see more clearly. Good statistics are like a telescope for an astronomer, a microscope for a bacteriologist, or an X-ray for a radiologist. If we are willing to let them, good statistics help us see things about the world around us and about ourselves – both large and small – that we would not be able to see in any other way.

In How to Make the World Add Up, Tim Harford draws on his experience as both an economist and presenter of the BBC’s radio show More or Less. He takes us deep into the world of disinformation and obfuscation, bad research and misplaced motivation to find those priceless jewels of data and analysis that make communicating with numbers worthwhile. Harford’s characters range from the art forger who conned the Nazis to the stripper who fell in love with the most powerful congressman in Washington, to famous data detectives such as John Maynard Keynes, Daniel Kahneman and Florence Nightingale. He reveals how we can evaluate the claims that surround us with confidence, curiosity and a healthy level of scepticism.

Using ten simple rules for understanding numbers – plus one golden rule – his extraordinarily insightful book shows how if we keep our wits about us, thinking carefully about the way numbers are sourced and presented, we can look around us and see with crystal clarity how the world adds up.

Tim Harford is an economist, journalist and broadcaster. He is author of The Next Fifty Things That Made the Modern Economy, Messy, and the million-selling The Undercover Economist. Tim is a senior columnist at the Financial Times, and the presenter of Radio 4’s More or Less, the iTunes-topping series ‘Fifty Things That Made the Modern Economy’, and the new podcast ‘Cautionary Tales’. Tim has spoken at TED, PopTech and the Sydney Opera House. He is an associate member of Nuffield College, Oxford and an honorary fellow of the Royal Statistical Society. Tim was made an OBE for services to improving economic understanding in the New Year honours of 2019.

Useful Links:

‘If you aren’t in love with stats before reading this book, you will be by the time you’re done. Powerful, persuasive, and in these truth-defying times, indispensable’ – Caroline Criado Perez

‘Nobody makes the statistics of everyday life more fascinating and enjoyable than Tim Harford’ – Bill Bryson

‘Fabulously readable, lucid, witty and authoritative... Every politician and journalist should be made to read this book, but everyone else will get so much pleasure and draw so much strength from the joyful way it dispels the clouds of deceit and delusion’ – Stephen Fry

‘Wise, humane and, above all, illuminating. Nobody is better on statistics and numbers – and how to make sense of them’ – Matthew Syed

"There is a short-term penalty and a long-term reward to contrarianism, " Tim Harford tells The Investors Chronicle Interviews podcast.
Tim Harford says a grasp of statistics is more important than ever in the age of coronavirus, in an interview with Susie Mesure of the i. 
The pandemic has shown how a lack of solid statistics can be dangerous. But even with the firmest of evidence, we often end up ignoring the facts we don’t like, writes Tim Harford for The Guardian.
Barely one in 1,000 Britons has died from coronavirus — and yet the economy is in cardiac arrest, Government debt has run into hundreds of billions and many parents are terrified of sending their children to school— writes Tim Harford for the Daily Mail.
So, I've Been Thinking...
Happy Birthday Harold Davenport
The great Cantabrigian Harold Davenport is believed to have been the first to calculate the surprising statistic that only 23 people need be gathered together for there to be a 50% probability that two have them will have the same birthday. This work has however been somewhat undermined by rolling lockdowns, which make such a gathering seem unimaginable for the foreseeable future.

It has been suggested that many of our false beliefs are the result of the apparent inability, demonstrated by the birthday problem, most of us have in predicting such probabilities. And that many so-called anomalistic experiences can be explained away by the high probability of such so-called coincidences occurring when the Law of Large Numbers, as opposed to the rule of six, is in force.

Telephone telepathy, where you think about someone you haven’t heard from for a while shortly before they call you, and precognitive dreams, where you dream about something just before it happens in reality, are phenomena that yield easily to this law of large numbers: with some 7.8 billion people on the planet, how unlikely is it for someone somewhere to have such experiences?

There are, for example, over 21 million people on the planet today who share a birthday with Harold Davenport, and while it would seem to me to be something of a curious coincidence if I were one of them, this is only because of an egocentrism which leads me to falsely believe that my experience is not equivalent to that of any of those other 21 million.

Whether or not a poor grasp of probability really does contribute to false beliefs in psychic powers and if it does how big a factor it is, is unclear from the current research. One thing that is clear however is that, while I do not share a birthday with Harold Davenport, the fact that I am, as I have just noticed, writing this on that very day is a curious coincidence of absolutely no significance.

Chris Gyford, Cambridge Skeptics

Why You Gotta Be So Mean?

Controversial Cantabrigian Francis Galton, who balanced out his contributions to statistics by also pioneering eugenics, observed that extreme characteristics in parents such as height are not entirely inherited by their children, who tend to be closer to, what he termed, mediocrity. This phenomena, thankfully redubbed regression to the mean, has subsequently been widely observed.

Everything from sports performances to medical conditions seem to display a cyclical nature, where highs and lows tend to be followed by a return to the baseline. The high points and low points are, however, also the points at which we tend to take interventional action, and the post hoc attribution of the intervention for the subsequent return to the baseline is known as a regression fallacy.

Common situations for possible misattribution include a drop in the frequency of accidents at a blackspot after the instillation of speed cameras there, a rise in a failing student’s test scores after punishment is administered and the sophomore slump of an exciting new sports star. Without proper controls in place it is impossible to know the correct attribution.

Examples from the world of scepticism include an end to a slump in your golf scores after donning of a holographic wrist band, the end of a particularly bad bought of back pain after the consumption of sugar pills and the end of a long drought after intercessory prayer. In such cases it seems warranted to provisionally accept regression to the mean as the most reasonable explanation.

We must, of course, be careful not to misapply this fallacy; Galton’s failure to achieve the lasting greatness his work in statistics and other fields should have brought is more likely due to his championing of eugenics than regression to the mean. In science and medicine control groups are used to counter this phenomena, but for the rest of us long term records are needed to benchmark these patterns.

Chris Gyford, Cambridge Skeptics

While much has been written about those accused of witchcraft in Salem, a modern understanding of psychology can shed light on the reports of their alleged 'victims', writes Ara Eagan for The Skeptic.
We shouldn't be overly worried by the data showing that coronavirus antibodies wane after infection, explains immunologist Professor Sheena Cruickshank for The Skeptic.
Endometriosis affects one in ten women – yet patients continue to face an uphill battle for diagnosis and treatment – writes Alice Howarth for The Skeptic.
Rose-tinted references to the 'Spirit of the Blitz' miss the real story of deep inequality, and of progress built through campaigning and protesting, writes Victoria Stiles for The Skeptic.
Water fluoridation isn’t a magic bullet to end dental decay, but for some it may be the only dental care they have access to - and for that reason it's worth it - writes Shaun Sellars for The Skeptic.
In celebration of the career of James Randi, The Skeptic's editors and supporters share their memories of the quintessential skeptical icon, writes Michael Marshall.
Join psychology professors Richard Wiseman and Chris French for a Halloween discussion on apparitional experiences. This talk, which was streamed live on 31st October 2020, is now available for catch up on the SitP Online YouTube channel.
Join naturopath turned critic Britt Hermes for this Halloween-themed talk on the horrors and spooky practices of her former profession. This talk, which was streamed live on 29th October 2020, is now available for catch up on the SitP Online YouTube channel.
Join philosopher Aaron Rabinowitz to find out why skeptics should believe that ethics is real and free will is not. This talk, which was streamed live on 22nd October 2020, is now available for catch up on the SitP Online YouTube channel.
Join research scientist Dr. Brooke Magnanti, aka Belle de Jour, for her insights into the #SaveTheChildren movement. This talk, which was streamed live on 15th October 2020, is now available for catch up on the SitP Online YouTube channel.
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