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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Our union backed Brexit, but that doesn't mean scrapping freedom of movement

We can only improve the lives of our members, like those planning stike action at McDonalds, through solidarity.

The campaign to defend and extend free movement – highlighted by the launch of the Labour Campaign for Free Movement this month – is being seen in some circles as a back door strategy to re-run the EU referendum. If that was truly the case, then I don't think Unions like mine (the BFAWU) would be involved, especially as we campaigned to leave the EU ourselves.

In stark contrast to the rhetoric used by many sections of the Leave campaign, our argument wasn’t driven by fear and paranoia about migrant workers. A good number of the BFAWU’s membership is made up of workers not just from the EU, but from all corners of the world. They make a positive contribution to the industry that we represent. These people make a far larger and important contribution to our society and our communities than the wealthy Brexiteers, who sought to do nothing other than de-humanise them, cheered along by a rabid, right-wing press. 

Those who are calling for end to freedom of movement fail to realise that it’s people, rather than land and borders that makes the world we live in. Division works only in the interest of those that want to hold power, control, influence and wealth. Unfortunately, despite a rich history in terms of where division leads us, a good chunk of the UK population still falls for it. We believe that those who live and work here or in other countries should have their skills recognised and enjoy the same rights as those born in that country, including the democratic right to vote. 

Workers born outside of the UK contribute more than £328 million to the UK economy every day. Our NHS depends on their labour in order to keep it running; the leisure and hospitality industries depend on them in order to function; the food industry (including farming to a degree) is often propped up by their work.

The real architects of our misery and hardship reside in Westminster. It is they who introduced legislation designed to allow bosses to act with impunity and pay poverty wages. The only way we can really improve our lives is not as some would have you believe, by blaming other poor workers from other countries, it is through standing together in solidarity. By organising and combining that we become stronger as our fabulous members are showing through their decision to ballot for strike action in McDonalds.

Our members in McDonalds are both born in the UK and outside the UK, and where the bosses have separated groups of workers by pitting certain nationalities against each other, the workers organised have stood together and fought to win change for all, even organising themed social events to welcome each other in the face of the bosses ‘attempts to create divisions in the workplace.

Our union has held the long term view that we should have a planned economy with an ability to own and control the means of production. Our members saw the EU as a gravy train, working in the interests of wealthy elites and industrial scale tax avoidance. They felt that leaving the EU would give the UK the best opportunity to renationalise our key industries and begin a programme of manufacturing on a scale that would allow us to be self-sufficient and independent while enjoying solid trading relationships with other countries. Obviously, a key component in terms of facilitating this is continued freedom of movement.

Many of our members come from communities that voted to leave the EU. They are a reflection of real life that the movers and shakers in both the Leave and Remain campaigns took for granted. We weren’t surprised by the outcome of the EU referendum; after decades of politicians heaping blame on the EU for everything from the shape of fruit to personal hardship, what else could we possibly expect? However, we cannot allow migrant labour to remain as a political football to give succour to the prejudices of the uninformed. Given the same rights and freedoms as UK citizens, foreign workers have the ability to ensure that the UK actually makes a success of Brexit, one that benefits the many, rather than the few.

Ian Hodon is President of the Bakers and Allied Food Workers Union and founding signatory of the Labour Campaign for Free Movement.