Trading kidneys, repugnant markets and stable marriages win the Nobel Prize in Economics

Roth and Shapley charted a course for economists to go beyond simply arguing for markets in everything.

The 2012 Nobel Prize in Economics - technically the Sveriges Riksbank Prize in Economic Sciences in Memory of Alfred Nobel, but nobody cares - has been awarded to two American Economists, Alvin Roth and Lloyd Shapley "for the theory of stable allocations and the practice of market design". The Nobel Committee explains what that means:

This year's Prize concerns a central economic problem: how to match different agents as well as possible. For example, students have to be matched with schools, and donors of human organs with patients in need of a transplant. How can such matching be accomplished as efficiently as possible? What methods are beneficial to what groups? The prize rewards two scholars who have answered these questions on a journey from abstract theory on stable allocations to practical design of market institutions.

Lloyd Shapley used so-called cooperative game theory to study and compare different matching methods. A key issue is to ensure that a matching is stable in the sense that two agents cannot be found who would prefer each other over their current counterparts. Shapley and his colleagues derived specific methods – in particular, the so-called Gale-Shapley algorithm – that always ensure a stable matching. These methods also limit agents' motives for manipulating the matching process. Shapley was able to show how the specific design of a method may systematically benefit one or the other side of the market.

Alvin Roth recognized that Shapley's theoretical results could clarify the functioning of important markets in practice. In a series of empirical studies, Roth and his colleagues demonstrated that stability is the key to understanding the success of particular market institutions. Roth was later able to substantiate this conclusion in systematic laboratory experiments. He also helped redesign existing institutions for matching new doctors with hospitals, students with schools, and organ donors with patients. These reforms are all based on the Gale-Shapley algorithm, along with modifications that take into account specific circumstances and ethical restrictions, such as the preclusion of side payments.

Even though these two researchers worked independently of one another, the combination of Shapley's basic theory and Roth's empirical investigations, experiments and practical design has generated a flourishing field of research and improved the performance of many markets. This year's prize is awarded for an outstanding example of economic engineering.

The committee have yet again reaffirmed the old adage that the most important thing to do when trying for a nobel prize is to live long enough that your achievements are recognised. The Gale-Shapley algorithm, for instance, was devised in 1962, when Lloyd Shapley was 34. It concerns a maths problem known as the stable marriage problem: if you have an even number of men and women, can you always come up with a set of marriages where there are no two people of opposite sex who would both rather have each other than their current partners? (1960s maths problems: usually heteronormative.) If you can, then the marriage is "stable".

The Gale-Shapley algorithm is a way of always ensuring stable matches; and much of Shapley's work covers the same areas, straddling the boundaries between economics, mathematics, and computer science.

Roth is the younger of the two winners, and works in a far more empirical sphere. As the committee points out, although the two men never actually collaberated, Roth took Shapley's theoretical work and applied it to actually existing markets. For instance, Roth used the Gale-Shapley agorithm to ease the kidney shortage in the US. David Wessel explains (£):

As of noon yesterday, 58,470 people in the U.S. were waiting for a kidney transplant. Most won't get one this year. There aren't enough donated kidneys to go around. Surgeons transplanted just 15,129 kidneys last year. Now a band of transplant surgeons and economists are trying to fix that by creating a moneyless market for exchanging kidneys. Most transplanted kidneys come from a person who has died, a supply that grows slowly because of ignorance about the need for donations or grieving relatives' reluctance. But a kidney taken from a live donor works better, and almost everyone has a spare. As techniques improve for removing healthy kidneys and for suppressing the body's tendency to reject a transplant, doctors increasingly turn to kidneys from living donors, usually relatives. Last year, 43% of kidneys transplanted in the U.S. came from living donors, up from 28% a decade ago. But a biological barrier often blocks a transplant from a relative. In about a third of all would-be pairs, blood types are incompatible. In others, the sick person has antibodies that can initiate a rejection of the donated organ. It's heartbreaking "to have the treasure of the live donor and then have that not go forward because of a biological obstacle," says Massachusetts General Hospital transplant surgeon Francis DelMonico.

Occasionally, transplant centers spot a way out: One New England father with blood type A couldn't donate a kidney to his daughter with blood type B. So he gave a kidney to a teenager with blood type A, and the teenager's sister gave a kidney for the man's daughter. New England's transplant centers have done six such exchanges. Baltimore's Johns Hopkins University has done seven.

The crucial thing about Roth's work, from an economic point of view, is that it involves finding stable allocations using market-like situations without involving money. The kidney swaps in the New England situation are market-like, trading kidneys for kidneys in a way that makes all parties better-off, but they don't actually require kidneys to be bought and sold.

We can see the importance of this by looking at another paper of Roth's, not cited by the committee, on repugnance in markets (pdf). Roth demonstrates that some markets are limited because the very existance of a market in some goods is considered repugnant. He argues, for instance, that the trade in horse meat being banned in California is not done through fears that eating horse meat is unsafe; nor is it done for animal welfare reasons, since it is still legal to farm and kill horses. But banned it is, and Roth argues that the natural response of economists to situations of this type - to argue for freer markets - is wrong, since it ignores the very strong feelings involved in the situation. Instead:

Being aware of the sources of repugnance can only help make such discussions more productive, not least because it can help separate the issues that are fundamentally empirical—like the degree of crowding out of altruistic donations that might result from different incentive schemes compared to how much new supply might be produced—from areas of disagreement that are not primarily empirical.

Hopefully his new Nobel Prize should give that argument greater weight in the years ahead.

A patient receives a kidney in Johns Hopkins university in Baltimore. 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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The footie is back. Three weeks in and what have we learned so far?

Barcleys, boots and big names... the Prem is back.

Another season, another reason for making whoopee cushions and giving them to Spurs fans to cheer them up during the long winter afternoons ahead. What have we learned so far?

Big names are vital. Just ask the manager of the Man United shop. The arrival of Schneiderlin and Schweinsteiger has done wonders for the sale of repro tops and they’ve run out of letters. Benedict Cumberbatch, please join Carlisle United. They’re desperate for some extra income.

Beards are still in. The whole Prem is bristling with them, the skinniest, weediest player convinced he’s Andrea Pirlo. Even my young friend and neighbour Ed Miliband has grown a beard, according to his holiday snaps. Sign him.

Boots Not always had my best specs on, but here and abroad I detect a new form of bootee creeping in – slightly higher on the ankle, not heavy-plated as in the old days but very light, probably made from the bums of newborn babies.

Barclays Still driving me mad. Now it’s screaming from the perimeter boards that it’s “Championing the true Spirit of the Game”. What the hell does that mean? Thank God this is its last season as proud sponsor of the Prem.

Pitches Some groundsmen have clearly been on the weeds. How else can you explain the Stoke pitch suddenly having concentric circles, while Southampton and Portsmouth have acquired tartan stripes? Go easy on the mowers, chaps. Footballers find it hard enough to pass in straight lines.

Strips Have you seen the Everton third kit top? Like a cheap market-stall T-shirt, but the colour, my dears, the colour is gorgeous – it’s Thames green. Yes, the very same we painted our front door back in the Seventies. The whole street copied, then le toot middle classes everywhere.

Scott Spedding Which international team do you think he plays for? I switched on the telly to find it was rugby, heard his name and thought, goodo, must be Scotland, come on, Scotland. Turned out to be the England-France game. Hmm, must be a member of that famous Cumbrian family, the Speddings from Mirehouse, where Tennyson imagined King Arthur’s Excalibur coming out the lake. Blow me, Scott Spedding turns out to be a Frenchman. Though he only acquired French citizenship last year, having been born and bred in South Africa. What’s in a name, eh?

Footballers are just so last season. Wayne Rooney and Harry Kane can’t score. The really good ones won’t come here – all we get is the crocks, the elderly, the bench-warmers, yet still we look to them to be our saviour. Oh my God, let’s hope we sign Falcao, he’s a genius, will make all the difference, so prayed all the Man United fans. Hold on: Chelsea fans. I’ve forgotten now where he went. They seek him here, they seek him there, is he alive or on the stairs, who feckin’ cares?

John Stones of Everton – brilliant season so far, now he is a genius, the solution to all of Chelsea’s problems, the heir to John Terry, captain of England for decades. Once he gets out of short trousers and learns to tie his own laces . . .

Managers are the real interest. So refreshing to have three young British managers in the Prem – Alex Neil at Norwich (34), Eddie Howe at Bournemouth (37) and that old hand at Swansea, Garry Monk, (36). Young Master Howe looks like a ball boy. Or a tea boy.

Mourinho is, of course, the main attraction. He has given us the best start to any of his seasons on this planet. Can you ever take your eyes off him? That handsome hooded look, that sarcastic sneer, the imperious hand in the air – and in his hair – all those languages, he’s so clearly brilliant, and yet, like many clever people, often lacking in common sense. How could he come down so heavily on Eva Carneiro, his Chelsea doctor? Just because you’re losing? Yes, José has been the best fun so far – plus Chelsea’s poor start. God, please don’t let him fall out with Abramovich. José, we need you.

Hunter Davies is a journalist, broadcaster and profilic author perhaps best known for writing about the Beatles. He is an ardent Tottenham fan and writes a regular column on football for the New Statesman.

This article first appeared in the 27 August 2015 issue of the New Statesman, Isis and the new barbarism