If you've got lucky, it's easy to convince people you're a sage

"Expert" predictions only need a few lucky guesses, then everyone believes them.

LSE's Nattavudh Powdthavee and Nanyang University's Yohanes E. Riyanto presented a paper last month titled Why Do People Pay for Useless Advice? (pdf) The authors demonstrate that people are prepared to pay for investment advice which they know cannot possibly be based on any real evidence – provided the advisor has got things right in the past.

Participants in the experiment were told to bet on five consecutive rounds of coin flips (they could pick the stake, provided it was higher than a minimum level and wouldn't make them lose all their money before the last round). Since they were using a fair coin, the chance of heads or tails coming up each time was 50-50, and the chance of someone calling the correct flips in all five rounds is one in thirty two. More importantly, no amount of expertise can help one predict the outcome of a sequence of coin tosses.

So when the participants were offered the chance to buy "predictions", you would expect them to ignore them. And most of them did, at least for round one (although even then, around 15 per cent of them did pay). But after the first round of tosses, everyone got to see their predictions, even those who hadn't paid. And for half the participants, those predictions were correct. Still, it's obviously just chance, right?

Apparently not so obvious. Those who got a correct "prediction" in round one were three times more likely to pay for one in round two than those who'd got an incorrect one. And by the time a subset of the group had got four correct predictions in a row, the possibility that they would buy a prediction for the fifth round had risen from 15 to 40 per cent.

In other words, just a few lucky guesses are all it takes to get people to pay for what the authors call "transparently useless advice". As they conclude:

Our experiment accurately describes how the real "false" experts typically operate in the information market, and the findings of this paper help to highlight how easy it is for an average person to form a belief in an expert when none may actually exist. 

Something worth bearing in mind next time you are looking at horse tips, stock pickers, or hedge funds, maybe.

George Bush tosses a coin. Is he an expert? Photograph: Getty Images

Alex Hern is a technology reporter for the Guardian. He was formerly staff writer at the New Statesman. You should follow Alex on Twitter.

Photo: Getty Images
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Autumn Statement 2015: whatever you hear, don't forget - there is an alternative

The goverment's programme of cuts is a choice, not a certainty, says Jolyon Maugham.

Later today you will hear George Osborne say there is no alternative to his plan to slash a further £20bn from lean public services by 2020-21. He will also say that there is no alternative to £9bn cuts to tax credits, cuts that will hit the poorest hardest, cuts of thousands of pounds per annum to the incomes of millions of households.

But there is.

As I outlined here the Conservatives plan future tax cuts which benefit, disproportionately or exclusively, the wealthy. Suspending those future tax cuts for the wealthy would say, by 2020-21, £9.3bn per annum.

I also explained here that a mere 50 of our 1,156 tax reliefs cost us over £100bn per annum. We don't know how much the other 1,106 reliefs cost us - because Government doesn't monitor them. And we don't know what public benefit they deliver - because Government doesn't check.

What we do know, as I explained here, is that they disproportionately and regressively benefit the wealthy: an average of £190,400 per annum for the wealthiest.

And we know, too, that they include (amongst the more than 1,000 uncosted reliefs) the £1bn plus “Rights for Shares Scheme” - badged by the Chancellor as for workers but identified by a leading law firm as designed for the wealthiest.

Simply by asking a question that the Chancellor chooses to ignore - do these 1,156 reliefs deliver value for money - it is entirely possible that £10bn or more extra in taxes could be collected without any loss of  public benefit

To this £19bn, we might add the indiscriminate provision - both direct and indirect - of public money to wealthy pensioners.

Those above basic state pension age enjoy a tax subsidy of up to 12% on earned income.

Moreover, this Office for National Statistics data (see Table 18) reveals that the 10% of wealthiest retired households - some 714,000 households - have gross pre-tax and pre-benefit private income of on average £43,983. Yet still they enjoy average cash benefits from government of £11,500 per annum.

Means testing benefits to exclude that top 10 per cent of retired households would save £8.2bn per annum. And why, you might wonder aloud, should means testing be thought by the government appropriate for the working age population, yet a heresy for retired households?

Add in abolition of that unprincipled tax subsidy and you'll save even more. 

So there are alternatives. Clear alternatives. Good alternatives. Alternatives that enable those with the broadest shoulders to bear some share of the pain. Don't allow yourself to be persuaded otherwise.

Jolyon Maugham is a barrister who advised Ed Miliband on tax policy. He blogs at Waiting for Tax, and writes for the NS on tax and legal issues.