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 joy of only winning once: why England should be proud of 1966

We feel the glory of that triumphant moment, 50 years ago, all the more because of all the other occasions when we have failed to win.

There’s a phrase in football that I really hate. It used to be “Thirty years of hurt”. Each time the England team crashes out of a major tournament it gets regurgitated with extra years added. Rather predictably, when England lost to Iceland in Euro 2016, it became “Fifty years of hurt”. We’ve never won the European Championship and in 17 attempts to win the World Cup we have only won once. I’m going to tell you why that’s a record to cherish.

I was seven in 1966. Our telly was broken so I had to watch the World Cup final with a neighbour. I sat squeezed on my friend Colin’s settee as his dad cheered on England with phrases like “Sock it to them Bobby”, as old fashioned now as a football rattle. When England took the lead for the second time I remember thinking, what will it feel like, when we English are actually Champions of the World. Not long after I knew. It felt good.

Wembley Stadium, 30 July 1966, was our only ever World Cup win. But let’s imagine what it would be like if, as with our rivals, we’d won it many times? Brazil have been World Champions on five occasions, Germany four, and Italy four. Most England fans would be “over the moon” if they could boast a similarly glorious record. They’re wrong. I believe it’s wonderful that we’ve only triumphed once. We all share that one single powerful memory. Sometimes in life less is definitely more.

Something extraordinary has happened. Few of us are even old enough to remember, but somehow, we all know everything that happened that day. Even if you care little about the beautiful game, I’m going to bet that you can recall as many as five iconic moments from 50 years ago. You will have clearly in your mind the BBC commentator Kenneth Wolstenholme’s famous lines, as Geoff Hurst tore down the pitch to score his hat-trick: “Some people are on the pitch. They think it’s all over. It is now”. And it was. 4 - 2 to England against West Germany. Thirty minutes earlier the Germans had equalised in the dying moments of the second half to take the game to extra time.

More drama we all share: Geoff Hurst’s second goal. Or the goal that wasn’t, as technology has since, I think, conclusively proved. The shot that crashed off the cross bar and did or didn’t cross the line. Of course, even if you weren’t alive at the time, you will know that the linesman, one Tofiq Bakhramov, from Azerbaijan (often incorrectly referred to as “Russian”) could speak not a word of English, signalled it as a goal.

Then there’s the England Captain, the oh-so-young and handsome Bobby Moore. The very embodiment of the era. You can picture him now wiping his muddy hands on his white shorts before he shakes hands with a youthful Queen Elizabeth. Later you see him lifted aloft by his team mates holding the small golden Jules Rimet trophy.

How incredible, how simply marvellous that as a nation we share such golden memories. How sad for the Brazilians and Germans. Their more numerous triumphs are dissipated through the generations. In those countries each generation will remember each victory but not with the intensity with which we English still celebrate 1966. It’s as if sex was best the first time. The first cut is the deepest.

On Colin’s dad’s TV the pictures were black and white and so were the flags. Recently I looked at the full colour Pathe newsreel of the game. It’s the red, white and blue of the Union Jack that dominates. The red cross of Saint George didn’t really come into prominence until the Nineties. The left don’t like flags much, unless they’re “deepest red”. Certainly not the Union Flag. It smacks of imperialism perhaps. In 1966 we didn’t seem to know if we were English or British. Maybe there was, and still is, something admirable and casual about not knowing who we are or what is our proper flag. 

Twelve years later I’m in Cuba at the “World Festival of Youth” – the only occasion I’ve represented my country. It was my chance to march into a stadium under my nation’s flag. Sadly, it never happened as my fellow delegates argued for hours over what, if any, flag we British should walk behind. The delegation leaders – you will have heard of them now, but they were young and unknown then – Peter Mandelson, Trevor Phillips and Charles Clarke, had to find a way out of this impasse. In the end, each delegation walked into the stadium behind their flag, except the British. Poor Mandelson stood alone for hours holding Union Jack, sweltering in the tropical sun. No other country seemed to have a problem with their flag. I guess theirs speak of revolution; ours of colonialism.

On Saturday 30 July BBC Radio 2 will commemorate the 50th anniversary of the 1966 World Cup Final, live from Wembley Arena. Such a celebration is only possible because on 16 occasions we failed to win that trophy. Let’s banish this idea of “Fifty years of hurt” once and for all and embrace the joy of only winning once.

Phil Jones edits the Jeremy Vine Show on BBC Radio 2. On Saturday 30 July the station celebrates the 50th anniversary of the 1966 World Cup Final live from Wembley Arena, telling the story of football’s most famous match, minute by minuteTickets are available from: www.wc66.org