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.

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Donald Trump vs Barack Obama: How the inauguration speeches compared

We compared the two presidents on trade, foreign affairs and climate change – so you (really, really) don't have to.

After watching Donald Trump's inaugural address, what better way to get rid of the last few dregs of hope than by comparing what he said with Barack Obama's address from 2009? 

Both thanked the previous President, with Trump calling the Obamas "magnificent", and pledged to reform Washington, but the comparison ended there. 

Here is what each of them said: 

On American jobs

Obama:

The state of our economy calls for action, bold and swift.  And we will act, not only to create new jobs, but to lay a new foundation for growth.  We will build the roads and bridges, the electric grids and digital lines that feed our commerce and bind us together.  We'll restore science to its rightful place, and wield technology's wonders to raise health care's quality and lower its cost.  We will harness the sun and the winds and the soil to fuel our cars and run our factories.  And we will transform our schools and colleges and universities to meet the demands of a new age.

Trump:

For many decades we've enriched foreign industry at the expense of American industry, subsidized the armies of other countries while allowing for the very sad depletion of our military.

One by one, the factories shuttered and left our shores with not even a thought about the millions and millions of American workers that were left behind.

Obama had a plan for growth. Trump just blames the rest of the world...

On global warming

Obama:

With old friends and former foes, we'll work tirelessly to lessen the nuclear threat, and roll back the specter of a warming planet.

Trump:

On the Middle East:

Obama:

To the Muslim world, we seek a new way forward, based on mutual interest and mutual respect. To those leaders around the globe who seek to sow conflict, or blame their society's ills on the West, know that your people will judge you on what you can build, not what you destroy. 

Trump:

We will re-enforce old alliances and form new ones and unite the civilized world against radical Islamic terrorism, which we will eradicate completely from the face of the earth.

On “greatness”

Obama:

In reaffirming the greatness of our nation we understand that greatness is never a given. It must be earned.

Trump:

America will start winning again, winning like never before.

 

On trade

Obama:

This is the journey we continue today.  We remain the most prosperous, powerful nation on Earth.  Our workers are no less productive than when this crisis began.  Our minds are no less inventive, our goods and services no less needed than they were last week, or last month, or last year.  Our capacity remains undiminished.  

Trump:

We must protect our borders from the ravages of other countries making our product, stealing our companies and destroying our jobs.

Protection will lead to great prosperity and strength. I will fight for you with every breath in my body, and I will never ever let you down.

Stephanie Boland is digital assistant at the New Statesman. She tweets at @stephanieboland