Alvin E. Roth – Who Gets What ― and Why: The New Economics of Matchmaking and Market Design

Alvin E. Roth – Who Gets What ― and Why: The New Economics of Matchmaking and Market Design

Roth co-won the 2012 economics Nobel. His work focuses on solving coordination problems in markets. His most famous work is on matching donors and recipients for kidney transplants. But his insights also apply to other areas from matching college dorm roommates to football bowl game opponents, to marriage matchmaking, to residency and internship assignments for medical school graduates.

He has also greatly improved K-12 school placement systems in cities that allow a limited amount of school choice, such as New York City. In ranked-choice systems, many parents found it in their interest to rank their choices not in their actual order of preference. This level of gamesmanship gummed up the works for both parents and schools, and prevented honest signals from being sent. Borrowing from auction theory, Roth devised a lottery system that worked best when parents honestly ranked their order of preference when applying for schools. This made life simpler for parents, students, and schools, lowered the transaction costs of engaging in the lottery system, and made for better matches all around. Roth advises that similar lessons apply to students applying to college. Apply to the best schools you can, but don’t do early admission unless you have enough information to know that’s your best match. At the same time, apply to some “safe schools” since the better schools tend to be more competitive.

Crucial to Roth’s work is his distinction between thick and thin markets. Thick markets have numerous buyers and sellers with all manner of different preferences. Thin markets are much more difficult to find matches in. Some of the biggest challenges Roth has faced involved thin markets that lack a price system. For example, not only do kidney donations have to match the recipient’s blood type, it is illegal to compensate the donor in every country except, of all places, Iran.

This is where Roth falls short. The obvious solution is to allow price systems to emerge. As numerous economists have pointed out, banning compensated organ donations quite literally kills people. It is one of the most immoral policies a government can enforce. Roth’s work has consisted of second-best workarounds of these bad policies. He has saved hundreds, if not thousands of lives—his Nobel is well-earned. The trouble is that Roth is aware that his matchmaking work treats symptoms rather than problems, and seems content to leave it at that. He does not oppose paid organ donations. But he is also in no hurry to work to change social norms and government policy in a more humane direction.

The astute reader will notice that even in lower-stakes markets where Roth has worked on solving coordination problems, they tend to be either non-profit markets or markets that do not use money. He has devised brilliant systems to work around a lack of a price system, and some good rules of thumb that any non-price market designer can use. But, as with organs, in many cases the better solution is simply to introduce a price system where possible.

At one point, looking back on one of his more successful designs, Roth was proud to view himself as an engineer, rather than a mere student, seeking understanding. This is hubris on his part. Adam Smith famously warned that people are not chess pieces that can be moved around the board as a planner sees fit. The pieces have their own wants and desires. They move on their own in ways nobody can foresee. Roth’s second-best solutions are often improvements. But they are just that—second-best. Even the wisest, most compassionate designer cannot meet peoples’ needs as well as an honest price system can allow people to adapt and create for themselves, on their terms.


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