Crowdsourcing the unemployment rate

What's inflation going to be? Wanna bet?

"Wisdom of the crowds" is a pretty solid phenomenon. Ask a thousand people to guess the number of sweets in a jar, and the average (mean) of their guesses tends to be damn close to the actual number.

What's more interesting is whether the same idea works, not just to guesses, but to forecasts. Specifically, economic forecasts. If you ask a thousand people to guess what the unemployment rate will be in two years time, how will they do?

There are certainly reasons to be hopeful. Information is widely distributed, with little advantage accruing to experts; and in fact, unlike with simply counting sweets, there's likely to be a fair few people with "inside" information (hiring plans, perhaps, or a feel for how their sector is moving), which they may use to inform their guesses. Mix together enough guesses, and you could generate insight.

That's what the Adam Smith Institute and Paddy Power are hoping; the two have teamed up to offer markets in key UK economic statistics. You'll be able to bet on what the rate of inflation and unemployment will be in June 2015; the ASI's Sam Bowman writes that:

By combining the local knowledge of thousands of people, betting markets can outpredict any panel of experts. If these markets catch on, the government should consider outsourcing all of its forecasts to prediction markets instead of expert forecasters.

But there may still be some problems, both with the idea and its implementation.

Betting markets are indeed a theoretically great way of harnessing the wisdom of the crowds. As Bowman writes, the fact that people put money on their predictions means that more confident predictions are weighted higher, and vice versa. But the necessity of teaming up with a bookmaker to launch the idea means that there is a major distortion: the odds the bookie has set. Punters can get 7/2 that inflation will be greater than 5 per cent, and just 5/2 that it will be between 4.01 per cent and 5 per cent. That means that someone who thinks that inflation is most likely to be around 4.75 per cent may take advantage of the higher odds offered if they guess slightly higher. It also means that what Paddy Power think is most likely will skew the guesses.

A better version of the same idea would be to create a prediction market. The difference between the two is that in a market, the crowd takes the role of bookmaker as well as punter. The odds themselves get set procedurally, based purely on where people are betting, and so there's no chance of a bad guess on the bookies' part skewing the predictions.

But even if the market was designed to perfectly get the true thoughts of everyone in the crowd, there's still reasons to doubt that it can be that good at forecasting economic data.

There's quite a specific set of conditions which are required for crowdsourcing to work. James Surowiecki, who coined the phrase "wisdom of crowds", describes four: Diversity of opinion, independence of opinion, decentralisation of action, and aggregation of information. Of those, the one which is the most problematic in this case is independence. People's guesses aren't secret, and they affect others. That means you could end up seeing a circular mill, where everyone reinforces everyone else's beliefs to the extent that the crowdsourcing breaks down. Think: do you hold your beliefs about what might happen to the unemployment rate based on investigation of the primary data, or based on collation of expert analysis? If it's the latter, you'd be a net harm to the crowdsourcing, contributing largely to the flocking problem.

It would still be nice to get more financial bets. But that's mostly so that I could join in my sportier friends in having something where I feel like my expertise could win me a bit of cash; when it comes to actually trying to work out what will happen, we might have to stick with older methods.

Mark Carney. 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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Inside Big Ben: why the world’s most famous clock will soon lose its bong

Every now and then, even the most famous of clocks need a bit of care.

London is soon going to lose one of its most familiar sounds when the world-famous Big Ben falls silent for repairs. The “bonging” chimes that have marked the passing of time for Londoners since 1859 will fall silent for months beginning in 2017 as part of a three-year £29m conservation project.

Of course, “Big Ben” is the nickname of the Great Bell and the bell itself is not in bad shape – even though it does have a huge crack in it.

The bell weighs nearly 14 tonnes and it cracked in 1859 when it was first bonged with a hammer that was way too heavy.

The crack was never repaired. Instead the bell was rotated one eighth of a turn and a lighter (200kg) hammer was installed. The cracked bell has a characteristic sound which we have all grown to love.

Big Ben strikes. UK Parliament.

Instead, it is the Elizabeth Tower (1859) and the clock mechanism (1854), designed by Denison and Airy, that need attention.

Any building or machine needs regular maintenance – we paint our doors and windows when they need it and we repair or replace our cars quite routinely. It is convenient to choose a day when we’re out of the house to paint the doors, or when we don’t need the car to repair the brakes. But a clock just doesn’t stop – especially not a clock as iconic as the Great Clock at the Palace of Westminster.

Repairs to the tower are long overdue. There is corrosion damage to the cast iron roof and to the belfry structure which keeps the bells in place. There is water damage to the masonry and condensation problems will be addressed, too. There are plumbing and electrical works to be done for a lift to be installed in one of the ventilation shafts, toilet facilities and the fitting of low-energy lighting.

Marvel of engineering

The clock mechanism itself is remarkable. In its 162-year history it has only had one major breakdown. In 1976 the speed regulator for the chimes broke and the mechanism sped up to destruction. The resulting damage took months to repair.

The weights that drive the clock are, like the bells and hammers, unimaginably huge. The “drive train” that keeps the pendulum swinging and that turns the hands is driven by a weight of about 100kg. Two other weights that ring the bells are each over a tonne. If any of these weights falls out of control (as in the 1976 incident), they could do a lot of damage.

The pendulum suspension spring is especially critical because it holds up the huge pendulum bob which weighs 321kg. The swinging pendulum releases the “escapement” every two seconds which then turns the hands on the clock’s four faces. If you look very closely, you will see that the minute hand doesn’t move smoothly but it sits still most of the time, only moving on each tick by 1.5cm.

The pendulum swings back and forth 21,600 times a day. That’s nearly 8m times a year, bending the pendulum spring. Like any metal, it has the potential to suffer from fatigue. The pendulum needs to be lifted out of the clock so that the spring can be closely inspected.

The clock derives its remarkable accuracy in part from the temperature compensation which is built into the construction of the pendulum. This was yet another of John Harrison’s genius ideas (you probably know him from longitude fame). He came up with the solution of using metals of differing temperature expansion coefficient so that the pendulum doesn’t change in length as the temperature changes with the seasons.

In the Westminster clock, the pendulum shaft is made of concentric tubes of steel and zinc. A similar construction is described for the clock in Trinity College Cambridge and near perfect temperature compensation can be achieved. But zinc is a ductile metal and the tube deforms with time under the heavy load of the 321kg pendulum bob. This “creeping” will cause the temperature compensation to jam up and become less effective.

So stopping the clock will also be a good opportunity to dismantle the pendulum completely and to check that the zinc tube is sliding freely. This in itself is a few days' work.

What makes it tick

But the truly clever bit of this clock is the escapement. All clocks have one - it’s what makes the clock tick, quite literally. Denison developed his new gravity escapement especially for the Westminster clock. It decouples the driving force of the falling weight from the periodic force that maintains the motion of the pendulum. To this day, the best tower clocks in England use the gravity escapement leading to remarkable accuracy – better even than that of your quartz crystal wrist watch.

In Denison’s gravity escapement, the “tick” is the impact of the “legs” of the escapement colliding with hardened steel seats. Each collision causes microscopic damage which, accumulated over millions of collisions per year, causes wear and tear affecting the accuracy of the clock. It is impossible to inspect the escapement without stopping the clock. Part of the maintenance proposed during this stoppage is a thorough overhaul of the escapement and the other workings of the clock.

The Westminster clock is a remarkable icon for London and for England. For more than 150 years it has reminded us of each hour, tirelessly. That’s what I love about clocks – they seem to carry on without a fuss. But every now and then even the most famous of clocks need a bit of care. After this period of pampering, “Big Ben” ought to be set for another 100 or so years of trouble-free running.

The Conversation

Hugh Hunt is a Reader in Engineering Dynamics and Vibration at the University of Cambridge.

This article was originally published on The Conversation. Read the original article.