Thursday, September 23, 2021

Police assignments by seniority in Chicago

 Here's a recent NBER working paper reporting a study of the assignment of police officers in Chicago, where some officers can choose to transfer to newly vacant positions, with priority determined by seniority. The resulting allocation reveals that more senior officers move to assignments with lower levels of violent crime.

Police Officer Assignment and Neighborhood Crime  by Bocar Ba, Patrick Bayer, Nayoung Rim, Roman Rivera & Modibo Sidibé  WORKING PAPER 29243, DOI 10.3386/w29243,  September 2021

Abstract: We develop an empirical model of the mechanism used to assign police officers to Chicago districts and examine the efficiency and equity of alternative allocations. We document that the current bidding process, which grants priority based on seniority, results in the assignment of more experienced officers to less violent and high-income neighborhoods. Our empirical model combines estimates of heterogeneous officer preferences underlying the bidding process with causal estimates of the effects of officer experience on neighborhood crime. Equalizing officer seniority across districts would reduce violent crime rate by 4.6 percent and significantly decrease inequality in crime, discretionary arrests, and officer use of force across neighborhoods. Moreover, this assignment can be achieved in a revenue-neutral way while resulting in small welfare gains for police officers, implying that it is more equitable and efficient.

Wednesday, September 22, 2021

Congratulations to 51 new Econometric Society Fellows of 2021

 This year there are 51 new Fellows of the Econometric Society:

Congratulations to our 2021 Fellows  

Jaap Abbring, Tilburg University

Chunrong Ai, Chinese University of Hong Kong, Shenzhen

Ufuk Akcigit, University of Chicago

Simon Board, University of California, Los Angeles

Antonio Cabrales, Universidad Carlos III, Madrid

Arnaud Costinot, Massachusetts Institute of Technology

Peter Cramton, University of Cologne and University of Maryland (Emeritus)

Stefano Dellavigna, University of California, Berkeley

Prosper Dovonon, Concordia University, Montreal

Christian Dustmann, University College London

Graham Elliot, University of California, San Diego

Marcella Eslava, Universidad de los Andes

Armin Falk, University of Bonn

Oded Galor, Brown University

Yuriy Gorodnichenko, University of California, Berkeley

Veronica Guerrieri, University of Chicago

Luigi Guiso, Einaudi Institute for Economics and Finance

Bard Harstad, University of Oslo

Erik Hurst, University of Chicago

Patrick Kline, University of California, Berkeley

Fuhito Kojima, University of Tokyo

Botond Koszegi, Central European University

Rim Lahmandi-Ayed, University of Carthage

John Leahy, University of Michigan

Sydney Ludvigson, New York University

Ulrike Malmendier, University of California, Berkeley

Ramon Marimon, European University Institute

Alexandre Mas, Princeton University

Atif Mian, Princeton University

Magne Mogstad, University of Chicago

Benjamin Moll, London School of Economics

Sendhil Mullainathan, University of Chicago

Victor Murinde, SOAS University of London

Emi Nakamura, University of California, Berkeley

Volker Nocke, University of Mannheim

Nathan Nunn, Harvard University

Rohini Pande, Yale University

Bruce Preston, University of Melbourne

James Robinson, University of Chicago

Christina Romer, University of California, Berkeley

Antoinette Schoar, Massachusetts Institute of Technology

Matthew Shum, California Institute of Technology

Rohini Somanathan, Delhi School of Economics and University of Gothenberg

Stefanie Stantcheva, Harvard University

Wing Suen, University of Hong Kong

Balazs Szentes, London School of Economics

Silvana Tenreyro, London School of Economics

Aleh Tsyvinski, Yale University

Nicolas Vieille, HEC, Paris

Ebonya Washington, Yale University

Ekaterina Zhuravskaya, Paris School of Economics

 The Society is grateful for the work of its 2021 Fellows Nominating Committee consisting of Dirk Bergemann (Chair), Xiaohong Chen, Itzhak Gilboa, Kate Ho, Dilip Mookherjee, Monika Piazzesi, and Hélène Rey. 

Publication Date: Wednesday, September 22, 2021

Repugnance watch: Gender-affirming medical care for transgender adolescents becomes a crime in Arkansas

 Here's a recent article in repugnance to certain kinds of medical care involving transgender children as they approach puberty:

Increasing Criminalization of Gender-Affirming Care for Transgender Youths—A Politically Motivated Crisis by Benjamin C. Park, BS1; Rishub K. Das, BA1; Brian C. Drolet, MD, JAMA Pediatr. Published online September 13, 2021. doi:10.1001/jamapediatrics.2021.2969

"On April 6, 2021, Arkansas passed Act 626, to be known as the “Arkansas Save Adolescents From Experimentation (SAFE) Act,”1 thus becoming the first state to outlaw gender-affirming care (GAC) for transgender youth. Many other states are considering similar bills, some of which include provisions that impose criminal penalties on health care professionals.

"Although Act 626 is among the more severe examples of antitransgender legislation, the United States has a history of similar legislation. Since 2015, coordinated attacks against lesbian, gay, bisexual, transgender, and queer (LGBTQ) rights have escalated in an unprecedented fashion. The targets of these attacks have shifted from marriage equality, bathroom access, and sports participation to the most recent attacks on transgender youths and their bodies. Act 626 is a part of recent nationwide efforts to limit access to GAC for transgender youths. This year represents a critical time for transgender young people, with new bills targeting their access to health care in at least 21 states.

"Approximately 1.4 million adults (0.6% of adults in the United States) and 150 000 youths (0.7% of youths aged 13-17 years in the US) identify as transgender.2 A large body of research dedicated to transgender health indicates that GAC, including prescribing or using puberty blockers such as gonadotropin-releasing hormone agonists, (GnRHa), hormone therapy (eg, testosterone or estrogen therapy), and gender-affirming surgery, is medically necessary for patients experiencing gender dysphoria.3 The discordant effects of societal gender roles and gendered activities on transgender youths are exacerbated during puberty, when masculinizing and feminizing anatomical changes take place. Transgender youths may find that pubertal changes worsen the dissonance between their anatomy and their gender identity, contributing to gender dysphoria and increasing the risk for negative health outcomes."


You can find the bill here (the first link gives you the text of the bill in pdf):


The act is long and explains itself as protective of children from medical procedures it regards as unproven. This looks like the action paragraph directed at physicians:

"20-9-1502. Prohibition of gender transition procedures for minors.

"(a) A physician or other healthcare professional shall not provide gender transition procedures to any individual under eighteen (18) years of age.

"(b) A physician, or other healthcare professional shall not refer any 17 individual under eighteen (18) years of age to any healthcare professional for gender transition procedures."

Tuesday, September 21, 2021

Modern peer review: how it evolved since the 1950's in Sociology

 Peer review is a big part of the design of modern academic publishing in scholarly journals. It wasn't always that way, and the current peer review system is pretty modern. Here's an account of its development in the discipline of Sociology, since the 1950's (which is similar to what we see in Economics, except that it appears Sociology relies substantially more on double-blind reviews).

Merriman, B. Peer Review as an Evolving Response to Organizational Constraint: Evidence from Sociology Journals, 1952–2018. The American Sociologist 52, 341–366 (2021).

"Abstract: Double-blind peer review is a central feature of the editorial model of most journals in sociology and neighboring social scientific fields, yet there is little history of how and when its main features developed. Drawing from nearly 70 years of annual reports of the editors of American Sociological Association journals, this article describes the historical emergence of major elements of editorial peer review. These reports and associated descriptive statistics are used to show that blind review, ad hoc review, the formal requirement of exclusive submission, routine use of the revise and resubmit decision, and common use of desk rejection developed separately over a period of decades. The article then argues that the ongoing evolution of the review model has not been driven by intellectual considerations. Rather, the evolution of peer review is best understood as the product of continuous efforts to steward editors’ scarce attention while preserving an open submission policy that favors authors’ interests."

From the introduction:

"In the main, editors are faculty members who operate a journal concurrently with ordinary work responsibilities; some receive modest, fixed remuneration, but editors have no strong financial interest in the journals they edit, and commonly serve for fixed or periodically renewed terms. (For most current journals, the economic interest rests primarily with one of a handful of large commercial publishers.) Journals do not restrict submissions by status criteria such as institutional affiliation or academic rank, and submission ordinarily carries little or no money cost, even at journals where authors assume a large part of the eventual expense of publication. Authors are expected to submit a given work exclusively to a single journal. After initial screening, submissions to a typical journal undergo double-blind review, in which the identities of authors and reviewers are not known to one another. Most evaluations of submitted manuscripts are produced by scholars who are not part of the appointed editorial staff of the journal. Work that is published has ordinarily undergone at least one formal round of revision and resubmission in response to the substance of external evaluations.


"At ASA journals, blind review, external review, exclusive submission, the formal revise and resubmit decision, and a developmental (rather than advisory) model of assessment developed in succession over a period of more than 30 years. In the twenty-first Century, persistent difficulties in obtaining timely reviews prompted a rapid, order of magnitude increase in frequency of rejections without review, commonly called desk rejections. Blind review was the only feature of the present model adopted at an ASA journal with an explicitly stated, unambiguously intellectual aim. This article argues that the other features of the current peer review model emerged as improvised efforts to balance two competing organizational imperatives: editors must steward scarce time and attention, but have also sought to render reasonably timely decisions without a priori exclusion of large numbers of prospective authors or capricious rejection of submissions. This pattern in journal operations in many ways reflects larger structural changes in sociology: rapid expansion of the field in the mid-to-late twentieth Century was succeeded by increasing competition in the academic labor market and heightened publishing expectations for tenure and promotion."

A snippet from the body of the paper:

"Ad hoc review, in which manuscripts are referred to scholars not formally affiliated with the journal organization, did not become an integral feature of the ordinary reviewing process until the early 1970s. Before then, virtually all evaluations were produced by members of journal editorial boards. Exclusive submission to a single journal also did not become a rule until the 1970s, and there is suggestive evidence that simultaneous submission to multiple journals may have been somewhat common until that time.

"At first, reviewing was plainly intended to aid to the work of the editor; the occasional value of reviews to authors was taken as an incidental benefit. The evolution of a developmental model of review oriented toward the author was gradual, as was the emergence of the revise and resubmit decision as a nearly unavoidable intermediate step on the path to publication."


And in conclusion:

"A primary constraint on editorial innovation is, of course, the professional and status structure of academic disciplines. An extensive body of research on disciplines, and on higher educational institutions more generally, has shown a powerful isomorphic tendency: such structures tend to converge on a given form of practice even if all the actors are wholly aware of its inadequacies. Further, change in such practices will, under most circumstances, be slow: individual academic advancement involves regularly submitting oneself to the judgment of the more experienced members of a discipline according to the standards those more experienced scholars impose. Those who may have the freshest view of an intellectual field, and perhaps a greater impulse to explore new lines of work, also face the strongest pressures to invest their time and effort conservatively in the oldest means of publicizing their work.

"Efforts to change publishing norms therefore stand a much greater chance of success if they are adopted first, or early, by actors who occupy central places in a field, or if they are given the strong, credible endorsement of such actors (Starbuck 2016: 178). Conversations about academic publishing models, especially their relative unresponsiveness to changing circumstances in the twenty-first Century, often possess a degree of fatalism. But the development of editorial peer review itself is an important reminder of how rapidly a good idea may spread."

HT: Retraction Watch

Monday, September 20, 2021

Keeping the market for new economists thick: AEA guidelines on timing of interviews

 Below are some guidelines suggested by the American Economic Association for the conduct of this year's job market for new Ph.D.s

AEA Guidance on Timeline for 2021-22 Economics Job Cycle

"The AEA Executive Committee, in conjunction with its ad hoc Committee on the Job Market, recognizes that it is to the benefit of the profession if the job market for economists is thick, with many employers and job candidates participating in the same stages at the same time.  Moreover, the AEA's goals of fairness, inclusion, and diversity are fostered by having a timeline that remains widely accepted, even as public health conditions necessitate a virtual ASSA meeting again this year. With these goals in mind, and in light of inquiries from both students and departments about how to proceed, the Association asks that departments and other employers consider the following timeline for initial interviews and “flyouts” in the upcoming job cycle.

Interview invitations
The AEA suggests that employers wait to extend interview invitations until at least Thursday, December 2, 2021.

Rationale: the AEA will deliver signals from job candidates to employers on December 1. We suggest that employers review those signals and incorporate them into their decision-making before extending interview invitations. Job candidates from under-represented groups may lack informal networks and thus, may especially rely on the signals to convey their interest. Waiting to review the signals before issuing invitations promotes a fairer, more equitable process.

We also ask that all employers indicate on EconTrack when they have extended interview invitations; this allows candidates to learn about the status of searches without visiting websites posting crowd-sourced information and potentially inappropriate other content.

The AEA suggests that employers conduct initial interviews starting on Monday, January 3, 2022, and that all interviews take place virtually; i.e. either by phone or online (e.g. by Zoom). We suggest that interviews not take place during the AEA meeting itself (January 7-9, 2022).

Rationale: In the past, interviews were conducted in person at the AEA/ASSA meetings. This promoted thickness of the market, because most candidates and employers were present at the in-person meetings, but had the disadvantage of precluding both job candidates and interviewers from fully participating in AEA/ASSA sessions. Given that the 2022 AEA/ASSA meetings will be entirely virtual, we suggest that interviews NOT take place on the meeting dates to allow job candidates and interviewers to participate in the conference.

We recommend that employers wait until January 3 to interview candidates because job candidates may have teaching or TA responsibilities in December, and to ensure that candidates have accurate expectations of the timing of the stages of the market. An unraveling of the market works against the Association’s goal of having a thick market at each stage and also against candidates having uniform expectations of the market’s timing. All interviews should be conducted by phone or online to prevent risk of exposure to COVID, and to promote equity among the candidates.

Flyouts and offers
Flyouts and offers generally happen at times appropriate for the employer, and the AEA sees no reason to suggest otherwise.  We ask that all employers indicate on EconTrack when they have extended flyout invitations and closed their searches.

Job market institutions and mechanisms
Please keep in mind the various job market institutions and mechanisms created by the AEA to improve the job market:

Thank you for your attention to this initiative."

Sunday, September 19, 2021

Stanford welcomes students back to campus

Starting tomorrow, we'll have classes in person, indoors, masked.

Saturday, September 18, 2021

Surrogacy law under review in New Zealand

 From the U. of Canterbury:

Who are my parents? Why New Zealand’s ‘creaky’ surrogacy laws are overdue for major reform by Debra Wilson, Annick Masselot,  and Martha Ceballos 

"several separate pieces of legislation cover the two types of surrogacy: gestational, where the child is not genetically related to the surrogate parent; and traditional, where the child is genetically related.

The resulting legal confusion is now the subject of a Law Commission review, which proposes significant reform based on the guiding principle that “the best interests of the child should be paramount”.

Right now, that cannot be said of the way surrogate children and their parents are treated under law that even judges have described as “creaky” and “inadequate”.


Surrogacy is regulated through the Human Assisted Reproductive Technology Act, which prohibits commercial surrogacy and requires gestational surrogacy to be approved by an ethics committee.

But that act is silent on the legal parentage of the child, leaving this to be determined by the Status of Children Act. Effectively, the woman who gives birth and her partner (if the partner consents to the assisted reproduction) are the child’s legal parents.

This means the intended parents have no legal rights to the child – even if they are the genetic parents – until they adopt the child under the Adoption Act.

But legal parentage is important. Legal parents transfer citizenship to their children and act on their behalf, such as giving consent to medical treatment or travel."

Friday, September 17, 2021

Lectures on equilibrium in markets for indivisible goods at U. Tokyo by Teytelboym, Baldwin and Jagadeesan, Sept 21-24

 Towards a general theory of markets with indivisible goods: special lectures at The University of Tokyo Market Design Center (UTMD)

September 21-24, 2021 (Japan time) 


Fuhito Kojma, Director, UTokyo Market Design Center, and Professor, the University of Tokyo

Michihiro Kandori: Vice Director, UTokyo Market Design Center, and University Professor, the University of Tokyo

Yuichiro Kamada: Associate Professor, UC Berkeley, and Global Fellow, the University of Tokyo

Venue: Zoom online  Language: English


*All times shown below are Japan time.

*Each lecture will be followed by 30 minutes Q&A session.

Lecture 1 9/21 (Tue) 16:00-17:30

Introduction to Markets for Indivisible Goods (by Alexander Teytelboym)

In many settings, such as auctions, the indivisibility of goods is a key market feature. But in markets with indivisible goods, competitive equilibria might not exist.  We explore conditions, such as substitutability of goods, that ensure existence of competitive equilibria. We also discuss connections between conditions for existence, tâtonnement, and cooperative properties of equilibria.

Lecture 2 9/22 (Wed) 16:00-17:30

The geometry of preferences: demand types, equilibrium with Indivisibilities, and bidding languages (by Elizabeth Baldwin)

An equivalence theorem between geometric structures and utility functions allows new methods for understanding preferences. Our classification of valuations into “Demand Types”, incorporates existing definitions regarding the comparative statics of demand (substitutes, complements, “strong substitutes”, etc.) and permits new ones. Our Unimodularity Theorem generalises previous results about when competitive equilibrium exists for any set of agents whose valuations are all of a “demand type”. Contrary to popular belief, equilibrium is guaranteed for more classes of purely-complements, than of purely-substitutes, preferences. Our Intersection Count Theorem checks equilibrium existence for combinations of agents with specific valuations by counting the intersection points of geometric objects. Applications include the “Product-Mix Auction” introduced by the Bank of England in response to the financial crisis. In that context, we show that all substitutes preferences can be represented, and no other preferences can be represented, by appropriate sets of permitted bids in the Substitutes Product-Mix Auction language; an analogous result holds for strong substitutes, when we refine the characteristics of the language. These languages thus also provide new characterizations of (all) substitutes, and of strong substitutes, respectively.

Lecture 3 9/23 (Thu) 16:00-17:30 The Equilibrium Existence Duality (by Alexander Teytelboym)

We show that, with indivisible goods, the existence of competitive equilibrium fundamentally depends on agents’ substitution effects, not their income effects. Our Equilibrium Existence Duality allows us to transport results on the existence of competitive equilibrium from settings with transferable utility to settings with income effects. One consequence is that net substitutability—which is a strictly weaker condition than gross substitutability—is sufficient for the existence of competitive equilibrium. Further applications give new existence results beyond the case of (net) substitutes. Our results have implications for auction design.

Lecture 4 9/24 (Fri) 09:30-11:00 Matching and Prices (by Ravi Jagadeesan)

Indivisibilities and budget constraints are pervasive features of many matching markets. But gross substitutability — a standard condition on preferences in matching models — typically fails in such markets. To accommodate budget constraints and other income effects, we instead assume that agents’ preferences satisfy net substitutability. Although competitive equilibria do not generally exist in our setting, we show that stable outcomes always exist and are efficient. We illustrate how the flexibility of prices is critical for our results. We also discuss how budget constraints and other income effects affect the properties of standard auction and matching procedures, as well as of the set of stable outcomes.

  Recorded lecture will be posted on UTMD’s YouTube channel within 6 hours.


Thursday, September 16, 2021

David Grether, 1938-2021

 David Grether, a pioneer in experimental economics at Caltech has died.

Here's the initial Caltech announcement, promising more to come: 

David Grether, Caltech Frank Gilloon Professor of Economics, Emeritus, passed away on September 12. He was 82.

The paper of his that I remember best (and that I have taught whenever I cover preference reversals) is his incentivized replication of the preference reversals first noticed in hypothetical choice psychology experiments:

Grether, David M., and Charles R. Plott. "Economic theory of choice and the preference reversal phenomenon." The American Economic Review 69.4 (1979): 623-638.

Here are the papers he listed prominently on his web page:


"Mental Processes and Strategic Equilibration: An fMRI Study of Selling Strategies in Second Price Auctions" with C. Plott, D. Rowe, M. Sereno and J. Allman Experimental Economics Vol. 10 (2007) pp. 105-122

Sequencing strategies in large, competitive, ascending price automobile auctions: An experimental study with Charles R. Plott  Journal of Economic Behavior and Organization Vol. 71 (2009) pp.75-88

The preference reversal phenomenon: Response mode, markets and incentives, with James Cox. Economic Theory 7 (1996): 387-405.

Individual behavior and market performance. American Journal of Agricultural Economics 76 (1994): 1079--1083.

Are people Bayesian? Uncovering behavioral strategies, with Mahmoud A. El-Gamal. Journal of the American Statistical Association 90 (1995): 1127-1145.

Wednesday, September 15, 2021

School choice in Latin America, in BBC News Mundo

 A news story with an unusually detailed account of school choice algorithms discusses some of the issues in Latin America, in Spanish, in BBC News Mundo. (Google translate does an adequate job...).  One of the issues discussed is that geographic priorities for schools give wealthier families an advantage, and perpetuate geographic segregation.

Qué es el Mecanismo de Boston y por qué expertos denuncian que hay segregación en las asignaciones de escuelas en América Latina  Analía Llorente  BBC News Mundo

[G translate: What is the Boston Mechanism and why experts denounce that there is segregation in school assignments in Latin America]

Some snippets:

"The Boston mechanism allows for a lot of parenting strategy and that means that it generates a lot of inequalities " [says] Paula Jaramillo, Associate Professor in Economics at the Universidad de los Andes in Colombia


"The criticism is against the Boston Mechanism because it continues to be applied, but it is also against the deferred acceptance method because it is generating segregation at the neighborhood level," says Caterina Calsamiglia, a leader in the investigation of these methods.

"The specialist refers to the fact that a student obtains more points for his proximity to the preferred school, therefore he has a greater chance of being admitted to it.

"This creates one of the main strategies is the moving neighborhood, decision can only carry out families with middle income to high, creating inequality."


"In many places in Latin America the selection method is not even regulated, and where it is, they are not very transparent with parents in communicating the methods.

"We know a lot about what is done by cities in the United States, in Europe, in Asia, we don't know so much about Latin America," says Paula Jaramillo.


"In conclusion, the experts believe that there is no magic method that can be applied uniformly in the countries of the region to avoid segregation and inequality in school selection.

"They agree that the deferred acceptance method is the "fairest" but not perfect. There are many factors to take into account from the quality of the schools to their location."

Tuesday, September 14, 2021

Market design (I talk to the entering Ph.D. class at Escola Nacional de Administração Pública)

 Yesterday I gave what I think was the first lecture to the entering class of Ph.D. students at the Escola Nacional de Administração Pública (ENAP) in Brasilia.  I spoke about market design, using as my main examples school choice and kidney exchange.  Afterwards there was Q&A on a variety of subjects, including black markets and repugnance.

Here's a video (I start to speak around minute 8):

Monday, September 13, 2021

Compatible pairs are (slowly) benefitting from kidney exchange

 Two articles forthcoming in the American Journal of Tranplantation consider the slowly increasing use of kidney exchange by compatible pairs (which is a good thing, but has been a long time in coming).  Compatible pairs can get better-matched kidneys through exchange (which has long term benefits), and because compatible pairs are largely easy to match, they additionally help create matches for hard to match pairs.

Motivations and outcomes of compatible living donor-recipient pairs in paired exchange, by Valerie Chipman, Matthew Cooper, Alvin G. Thomas, Matthew Ronin, Brian Lee, Stuart Flechner, David Leeser, Dorry L. Segev, Didier A. Mandelbrot, Tyler Lunow-Luke, Shareef Syed, Garet Hil, Chris E. Freise, Amy D. Waterman, Garrett R. Roll  First published: 01 September 2021

This article has been accepted for publication and undergone full peer review but has not been through the copyediting, typesetting, pagination and proofreading process, which may lead to differences between this version and the Version of Record. Please cite this article as doi:10.1111/ajt.16821

Abstract: Increasing numbers of compatible pairs are choosing to enter paired exchange programs, but motivations, outcomes, and system-level effects of participation is not well described. Using a linkage of the SRTR and National Kidney Registry, we compared outcomes of traditional (originally incompatible) recipients to originally compatible recipients using the Kaplan-Meier method. We identified 154 compatible pairs. Most pairs sought to improve HLA matching. Compared to the original donor, actual donors were younger (39 vs. 50 years, p<0.001), less often female (52% vs. 68%, p<0.01), higher BMI (27 vs 25 kg/m², p=0.03), less frequently blood type O (36% vs. 80%, p<0.001), and had higher eGFR (99 vs. 94 mL/min/1.73 m², p=0.02), with a better LKDPI (median 7 vs. 22, p<0.001). We observed no differences in graft failure or mortality. Compatible pairs made 280 additional transplants possible, many in highly sensitized recipients with long wait times. Compatible pair recipients derived several benefits from paired exchange including better donor quality. Living donor pairs should receive counseling regarding all options available including kidney paired donation. As more compatible pairs choose to enter exchange programs, consideration should be given to optimizing compatible pair and hard-to-transplant recipient outcomes.


Rethinking incompatibility in kidney transplantation  Kyle R. Jackson, Dorry L. Segev

First published: 31 August 2021

This article has been accepted for publication and undergone full peer review but has not been through the copyediting, typesetting, pagination and proofreading process, which may lead to differences between this version and the Version of Record. Please cite this article as doi:10.1111/ajt.16826

Abstract: Donor/recipient incompatibility in kidney transplantation classically refers to ABO/HLA-incompatibility. Kidney paired donation (KPD) was historically established to circumvent ABO/HLA-incompatibility, with the goal of identifying ABO/HLA-compatible matches. However, there is a broad range of donor factors known to impact recipient outcomes beyond ABO/HLA-incompatibility, such as age and weight, and quantitative tools are now available to empirically compare potential living donors across many of these factors, such as the living donor kidney donor profile index (LKDPI). Moreover, the detrimental impact of mismatch at other HLA antigens (such as DQ) and epitope mismatching on post-transplant outcomes has become increasingly recognized. Thus, it is time for a new paradigm of incompatibility that considers all of these risks factors together in assessing donor/recipient compatibility and the potential utility for KPD. Under this new paradigm of incompatibility, we show how the LKDPI and other tools can be used to identify donor/recipient incompatibilities that could be improved through KPD, even for those with a traditionally ‘compatible’ living donor.

Sunday, September 12, 2021

A living kidney donor podcast by Ned Brooks

 Here's a link at which you can hear Ned Brooks, on the latest episode of Donor Diaries

"Ned is a high-profile activist for living kidney donation and the founder of The National Kidney Donors Organization.  Ned’s appearance on Freakonomics podcast and his TEDx Talk on living kidney donation are often mentioned by living kidney donors as an early inspiration for their donation."

Saturday, September 11, 2021

David Cooper to lead Econ at Iowa

 Iowa celebrates David Cooper as new head of Economics. (Iowa was a leading department in experimental economics, in the early days of experiments in economics).

Experimental economist David J. Cooper is new head of Tippie Department of Economics

"David J. Cooper, a leading researcher and widely published author in experimental economics, is the new departmental executive officer for the Department of Economics at the Tippie College of Business.

"Cooper, 54, comes to Iowa after 14 years on the faculty of the Florida State University College of Social Sciences and Public Policy. He has been the director of Florida State’s experimental social sciences cluster since 2011.

Amy Kristof-Brown, dean of the Tippie College of Business, says Cooper’s scholarly record as an experimental economist and his administrative experience running Florida State’s experimental social sciences cluster stood out.


"Cooper says that Tippie’s Department of Economics was one of the top 25 in the nation when he was in graduate school, and he said he is eager to lead a department that once produced such legendary economists as Frank Knight, Edward Chamberlin, and Howard Bowen, who would go on to become president of the University of Iowa.

“My goal is to build a cohesive group of researchers and give the department the recognition it once had,” he says."

Friday, September 10, 2021

Matching theory in the September issue of Games and Economic Behavior

 The September 2021 issue of Games and Economic Behavior (Volume 129, Pages 1-590) has five papers on matching theory.

In the order in which they appear:

An improved bound to manipulation in large stable matches  by Gustavo Saraiva rights and content

Abstract: This paper builds on Kojima and Pathak (2009)'s result of vanishing manipulability in large stable mechanisms. We show that convergence toward truth-telling in stable mechanisms can be achieved much faster if colleges' preferences are independently drawn from an uniform distribution. Another novelty from our results is that they can be applied to competitive environments in which virtually all vacancies end up being filled. So this paper adds evidence to the fact that, though stable matching mechanisms are not entirely strategy-proof, in practice, when the number of participants in the market is sufficiently large, they can be treated as being effectively strategy-proof.


How lotteries in school choice help to level the playing field by Christian Basteck, Bettina Klaus, Dorothea Kübler rights and content

Abstract: School authorities in the UK and the US advocate the use of lotteries to desegregate schools. We study a school choice mechanism employed in Berlin where a lottery quota is embedded in the immediate acceptance (IA) mechanism, and compare it to the deferred acceptance mechanism (DA) with a lottery quota. In both mechanisms, some seats are allocated based on academic achievement (e.g., grades), while seats in the lottery quota are allocated randomly. We find that, in theory, a lottery quota strengthens truth-telling in DA by eliminating non-truth-telling equilibria. Furthermore, the equilibrium outcome is stable for DA with a lottery but not for IA with a lottery. These predictions are borne out in the experiment. Moreover, the lottery quota leads to more diverse school populations in the experiment, as predicted. Students with the lowest grades profit more from the introduction of the lottery under IA than under DA.


Substitutes and stability for many-to-many matching with contracts  by Keisuke Bando, Toshiyuki Hirai, Jun Zhang rights and content

Abstract:We examine the roles of (slightly weakened versions of) the observable substitutability condition and the observable substitutability across doctors condition of Hatfield et al. (2021) in many-to-many matching with contracts. We modify the standard cumulative offer algorithm to find stable outcomes and prove new results on the existence of stable outcomes. It is remarkable that size monotonicity at the offer-proposing side is essential for the existence result under observable substitutability across doctors.


Slot-specific priorities with capacity transfers  by Michelle Avataneo and BertanTurhan

Abstract: In many real-world matching applications, there are restrictions for institutions either on priorities of their slots or on the transferability of unfilled slots over others (or both). Motivated by the need in such real-life matching problems, this paper formulates a family of practical choice rules, slot-specific priorities with capacity transfers (SSPwCT). These rules invoke both slot-specific priorities structure and transferability of vacant slots. We show that the cumulative offer mechanism (COM) is stable, strategy-proof and respects improvements with regards to SSPwCT choice rules. Transferring the capacity of one more unfilled slot, while all else is constant, leads to strategy-proof Pareto improvement of the COM. Following Kominers' (2020) formulation, we also provide comparative static results for expansion of branch capacity and addition of new contracts in the SSPwCT framework. Our results have implications for resource allocation problems with diversity considerations.


Stability in sequential matching with incomplete information by Fanqi Shi rights and content

Abstract: I study a two-period matching model where one side of the market (e.g. workers) have an option to invest and delay matching in the first period. Investment increases each agent's matching surplus in the second period, by a magnitude of the worker's investment ability in the match pair. Assuming each worker's investment ability is her private information that unfolds in the second period, I define a notion of sequential stability, and show that the set of sequentially stable outcomes is a superset of the complete information stable outcomes. Moreover, with transferable utility, as long as the cost of delay coincides on the same side of the market, efficient investment occurs in any sequentially stable outcome. When every agent shares the same cost of delay, efficient investment also occurs in any sequentially stable outcome with non-transferable utility. My analysis suggests that efficient investment is a robust prediction in sequential matching markets.

Thursday, September 9, 2021

Kidney exchange, in Microeconomic Insights

 The team at Microeconomic Insights has published an easy to read summary of my just published paper with Itai Ashlagi in the September issue of Management Science:

Kidney Exchange: An Operations Perspective

"No country is presently able to supply all the kidney transplants required by its population, and most people with kidney failure will die without receiving a transplant. Kidney exchange is a way to increase the number of transplants by allowing incompatible patient-donor pairs to exchange kidneys. For logistical reasons, early exchanges involved just two patient-donor pairs, but the rise in donors without a particular recipient in mind has enabled long chains of non-simultaneous transplants. However, barriers between kidney exchange programs, both within and across countries, continue to make it difficult to find matches for some patient-donor pairs. Breaking down these barriers will be challenging, but the potential rewards are large—both in terms of lives saved and reduced healthcare costs."


Here's a link to the original paper:

1. Itai Ashlagi and Alvin E. Roth, “Kidney Exchange:  an Operations Perspective,” Management Science, September 2021, Volume 67, Issue 9, September 2021, Pages 5301-5967, iii-iv, 


Here's a video of a lecture I gave about the paper in June to an INFORMS audience, starting at minute 2:55.

Wednesday, September 8, 2021

Participating in a Covid challenge trial: a participant's experience

 The WSJ's Jenny Strasburg has another story on British challenge trials of Covid-19:

Researchers Infect Volunteers With Coronavirus, Hoping to Conquer Covid-19. So-called challenge trials have long been used to study infections, but so far only the U.K. is doing them for Covid-19   By Jenny Strasburg

"On March 8, 23-year-old Jacob Hopkins, a U.K. university student, watched researchers enter his quarantine room’s airlocked entrance at London’s Royal Free Hospital. They wheeled a cart carrying a big red box, like a picnic cooler, labeled “biohazard.”


"A few days after the virus was dripped into his nose, he was shivering with a mild case of Covid-19, with the antiviral remdesivir pumped through a thin tube inserted into his arm. He spent 19 days in quarantine and said he felt fully recuperated a month later. He will ultimately be paid about £6,000, equivalent to $8,300, for that time, a year of follow-up tests and phone calls, and a parallel study he agreed to. Trial payments are based on U.K. living wages and go through ethical review."


"All volunteers are 18 to 30 years old and screened for known risk factors. They are isolated in quarantine suites with full-time medical care and specialized air systems to contain the virus. Researchers hope to publish peer-reviewed initial findings from the first phase of the challenge trials by this autumn.


"Researchers hope trial data will shed light on the durability of immune protection and how Covid-19 affects breathing, heart function, smell and concentration even before symptoms show. They say the model could test new vaccines and treatments head-to-head, eliminating weaker candidates before expensive, large-scale trials. Transmission data could help authorities prioritize who gets booster doses.


As an observer of repugnant/controversial transactions, I've been following the challenge trial discussion, including in particular about appropriate payments for participants.  There's a part of the medical ethics literature that worries that payments to volunteers might be 'coercive,' particularly to poor volunteers, and that payments should therefore be as small as possible, e.g. minimum wage payments for time spent, and that some things (such as risk) should not be compensated. My colleagues and I have been among those pointing out that there can also be ethical (as well as practical) issues involved in paying too little (or in providing too little post-trial medical care and insurance).

Here are some earlier posts focusing on articles I've coauthored about compensation for participation in challenge trials:

Thursday, October 29, 2020

Paying participants in challenge trials of Covid-19 vaccines, by Ambuehl, Ockenfels, and Roth

"we note that increasing hourly pay by a risk-compensation percentage as proposed in the target article provides compensation proportional to risk only if the risk increases proportionally with the number of hours worked. (Some risky tasks take little time; imagine challenge trials to test bulletproof vests.) "

Tuesday, September 7, 2021

Covid reduced transplants worldwide (but relatively little in the U.S.)

 The Covid pandemic reduced transplants, more in some countries than in others.  Here's a survey from  the Lancet, covering 22 countries (with more authors than countries):

COVID-19 pandemic and worldwide organ transplantation: a population-based study by Olivier Aubert, MD Daniel Yoo, MPH Dina Zielinski, PhD Emanuele Cozzi, MD Massimo Cardillo, MD Michael Dürr, MD Beatriz Domínguez-Gil, MD Elisabeth Coll, MD Margarida Ivo Da Silva, MD Ville Sallinen, MD Karl Lemström, MD Karsten Midtvedt, MD Camilo Ulloa, MD Franz Immer, MD Annemarie Weissenbacher, MD Natalie Vallant, MD Nikolina Basic-Jukic, MD Kazunari Tanabe, MD Georgios Papatheodoridis, PhD Georgia Menoudakou, MSc Martin Torres, MD Carlos Soratti, MD Daniela Hansen Krogh Carmen Lefaucheur, MD Gustavo Ferreira, MD Helio Tedesco Silva Jr, MD David Hartell, MA John Forsythe, MD Lisa Mumford, MSc Peter P Reese, MD François Kerbaul, MD Christian Jacquelinet, MD Serge Vogelaar, MD Vassilios Papalois, MD Alexandre Loupy, MD 

"In this population-based, observational, before-and-after study, we collected and validated nationwide cohorts of consecutive kidney, liver, lung, and heart transplants from 22 countries. Data were collected from Jan 1 to Dec 31, 2020, along with data from the same period in 2019. The analysis was done from the onset of the 100th cumulative COVID-19 case through to Dec 31, 2020. We assessed the effect of the pandemic on the worldwide organ transplantation rate and the disparity in transplant numbers within each country.


"Transplant activity in all countries studied showed an overall decrease during the pandemic. Kidney transplantation was the most affected, followed by lung, liver, and heart."


Here's a figure of percentage reduction in transplants, overall and by organ, for each country.  The U.S. performance was relatively good.

Monday, September 6, 2021

Contested forms of marriage: child marriage (and signaling), bride exchange (watta satta), and capture (ala kachuu in Kyrgyz, zij poj niam in Hmong)

 Recent changes in child marriage laws in some U.S. states have reminded me that it is just one of many forms of contested marriage around the world.

Here's an NBC report on child marriage laws in the U.S.:

A child marriage survivor helped ban the practice in New York, but 44 states still allow it Maya Brown

"Child marriage is when someone under the age of 18 becomes legally married to an adult. Such minors, more likely girls than boys, are often forced into marriage because of socioeconomic factors by families who want to minimize their economic burden or earn income as a result of the marriage, according to UNICEF. Religious and cultural norms also contribute to its ongoing practice.


"As of 2020, there were an estimated 285 million child brides in South Asia. About 59 percent of girls are married before the age of 18 in Bangladesh, 27 percent in India and 18 percent in Pakistan, according to data from Girls Not Brides. The Women’s Refuge Commission says South Asian families force their daughters into child marriage as it is perceived to be the best means to provide economic and physical security.

"Even though almost half of all women in South Asia aged 20-24 reported being married before the age of 18, the rates of child marriage are currently decreasing in the region. Amin stressed that child marriage does not happen only to South Asian women, but it also affects women in other countries.

"In Latin America and the Caribbean, about 1 in 4 women are married before 18. Most of the top 20 countries with the highest prevalence rates of child marriage are in Africa, with Niger having the highest child marriage rate in the world. In west and central Africa, about 41 percent of girls in the region marry before reaching the age of 18.

"It also greatly affects women in the U.S., as approximately 40 children are married each day in America. Nearly 300,000 minors under the age of 18 were legally married in the U.S. from 2000 to 2018, according to a recent study. States with the highest per-capita rates of child marriage include Arkansas, Idaho, Kentucky, Nevada and Oklahoma."


Here's a recent NBER paper exploring an intervention, based on the idea that early marriage may signal a girl is a traditional type (not a modern type), and that other ways of signaling this might reduce the incentive to marry early:

A Signal to End Child Marriage: Theory and Experimental Evidence from Bangladesh by Nina Buchmann, Erica M. Field, Rachel Glennerster, Shahana Nazneen & Xiao Yu Wang.  WORKING PAPER 29052, DOI 10.3386/w29052,  July 2021

Abstract: Child marriage remains common even where female schooling and employment opportunities have grown. We introduce a signaling model in which bride type is imperfectly observed but preferred types have lower returns to delaying marriage. We show that in this environment the market might pool on early marriage even when everyone would benefit from delay. In this setting, offering a small incentive can delay marriage of all treated types and untreated non-preferred types, while programs that act directly on norms can unintentionally encourage early marriage. We test these theoretical predictions by experimentally evaluating a financial incentive to delay marriage alongside a girls’ empowerment program designed to shift norms. As predicted, girls eligible for the incentive are 19% less likely to marry underage, as are nonpreferred type women ineligible for the incentive. Meanwhile, the empowerment program was successful in promoting more progressive gender norms but failed to decrease adolescent marriage and increased dowry payments.


Then there's bride exchange, apparently still extant in Pakistan and Afganistan: here's a paper from the AER that interprets it as a kind of hostage exchange...

Jacoby, Hanan G., and Ghazala Mansuri. 2010. "Watta Satta: Bride Exchange and Women's Welfare in Rural Pakistan." American Economic Review, 100 (4): 1804-25.

Abstract: Can marriage institutions limit marital inefficiency? We study the pervasive custom of watta satta in rural Pakistan, a bride exchange between families coupled with a mutual threat of retaliation. Watta satta can be seen as a mechanism for coordinating the actions of two sets of parents, each wishing to restrain their son-in-law. We find that marital discord, as measured by estrangement, domestic abuse, and wife's mental health, is indeed significantly lower in watta satta versus "conventional" marriage, but only after accounting for selection bias. These benefits cannot be explained by endogamy, a marriage pattern associated with watta satta. 


"In traditional societies, where women’s formal legal rights are often weak, divorce is strongly stigmatized, and there is a high premium on female virginity, bargaining power can shift radically in favor of the man once the woman commits herself to marriage. This fact should have implications for the form of the marriage “contract”; in particular, we would expect its ex ante provisions to reflect the interests of the wife and her family in deterring or mitigating ex post malfeasance on the part of the husband.

"In this paper, we argue that exchange marriage in rural Pakistan can play just such a role. Bride exchange, known locally as watta satta (literally, “give-take”), usually involves the simultaneous marriage of a brother-sister pair from two households. Remarkably, watta satta accounts for about a third of all marriages in rural Pakistan. Watta satta is more than just an exchange of daughters, however; it also establishes the shadow of mutual threat across the marriages. As the watta bride quoted above expresses so succinctly, a husband who mistreats his wife in this arrangement can expect his brother-in-law to retaliate in kind against his sister.


"in the end, the evidence is compelling that the peculiar institution of watta satta, with its mutual threat of reciprocity, protects the welfare of women in rural Pakistan."


Of course, bride exchange occurs for other reasons than hostage exchange.  A colleague of mine reports that his grandparents, who emigrated from India to the U.S. in the 1960's, were married in a bride exchange between two brother-sister pairs, whose purpose was to remove the requirement of dowries.  And I know of stories in which a potential bride was doing essential household tasks (e.g. taking care of a disabled brother) and a bride exchange allowed her to marry without those tasks becoming neglected.


And finally, let's not forget marriage by capture, still extant in central Asia, and within living memory a cause of cultural conflict among Hmong immigrants to California and Minnesota among other places.

Here's a very recent story from the Guardian:

Kidnapped, raped, wed against their will: Kyrgyz women’s fight against a brutal tradition. At least 12,000 women are still abducted and forced into marriage every year in Kyrgyzstan. But pressure is growing to finally end the medieval custom.  by Mauro Mondello, 30 Aug 2021

"Known as ala kachuu (“take and run”), the brutal practice of kidnapping brides has its roots in medieval times along the steppes of Central Asia, yet persists to this day. It has been banned in Kyrgyzstan for decades and the law was tightened in 2013, with sentences of up to 10 years in prison for those who kidnap a woman to force her into marriage (previously it was a fine of 2,000 soms, worth about $25).

"The new law has not curtailed the practice, however, and prosecutions are rare. Nevertheless, according to the human rights organisation Restless Beings: “This is a significant development, in that prior to this the sentence for stealing livestock was considerably more than that for ala kachuu.”

“A happy marriage begins by crying,” goes one Kyrgyz proverb, and those tears are of anger and terror at the start of a marriage for ala kachuu brides.

"Ala kachuu is practised in all the countries of Central Asia, but it is especially common in the rural areas of post-Soviet Kyrgyzstan, a predominantly Muslim nation of about 6 million people. During Soviet rule, the custom was rare and parents generally arranged marriages.

"Data from the Women Support Center, an organisation that fights for gender equality in the country, indicates that at least 12,000 marriages take place, and are consummated, every year against the will of the bride. (The figure is from a 2011 report and believed to be an underestimate). Men kidnap women, they say, to prove their manhood, avoid courtship (considered a tedious waste of time) and save the payment of the kalym, or dowry, which can cost the groom up to $4,000 (£3,000) in cash and livestock.

"After the ala kachuu, which in some cases can be a consensual “kidnapping” when a couple wishes to speed up the process of marriage, the brides are taken to the house of the future husband. The in-laws welcome the woman and force her to wear the jooluk, a white shawl that signifies submission to the bride’s new family. Then comes the wedding. About 80% of the girls kidnapped accept their fate, often on the advice of their parents.

"According to data from the Unicef office in Bishkek the percentage of girls aged 15 to 19 who become pregnant in Kyrgyzstan is among the highest in the region, while 13% of marriages take place before the age of 18, despite it being illegal. "


And of course courts think differently of immigrant customs and local customs:

Hmong 'marriage by capture' in the United States of America and ukuthwala in South Africa : unfolding discussions  by Lea Mwambene  Published Online:1 Jan 2020 Comparative and International Law Journal of Southern AfricaVol. 53, No. 3

Abstract: 'Marriage by capture' among the Hmong people in the United States of America and ukuthwala in South Africa both take the form of the mock abduction of a young woman for the purpose of a customary marriage. The noteworthy point about these two customary marriage practices is that, although Hmong marriage by capture takes place in the context of a minority community in a liberal state, and ukuthwala occurs in a postcolonial state, courts in these jurisdictions convert these marriage practices to the common law offences of rape, assault, and abduction. This article reflects on the accused-centred approach in the case of People v Moua, in which the court invoked the cultural defence, and the victim-centred approach in Jezile v S, which severed cultural values from the rights of the woman. It questions whether the two communities in question, in their respective liberal and postcolonial settings, influence the attitudes of the courts in cases involving rape, assault, and abduction charges. The main argument proffered is that both approaches may encourage communities to continue marriage abduction practices without bringing them to the attention of investigative organs, with adverse human rights implications for the women and girls affected. The ultimate purpose of this conversation, therefore, is to show how the approaches of the courts to the recognition or non-recognition of these customary practices affect the rights of girls and women who encounter institutions of law that alienate people belonging to minority cultural groups, and often perpetuate injustice.



Deirdre Evans-Pritchard & Alison Dundes Rentein, The Interpretation and Distortion of Culture: A Hmong Marriage by Capture Case in Fresno, California, 4 S. CAL. Interdisc.L. J. 1 (1994)

Different cultural practices and social norms can promote coordination failures and misunderstandings of the gravest sorts: here's a 1988 story from the Los Angeles Times, which starts with the same Fresno case as the above article, and goes on to a very different Minnesota case.

Immigrant Crimes : Cultural Defense--a Legal Tactic  BY MYRNA OLIVER, JULY 15, 1988

"Kong Moua, a Hmong tribesman from the hills of Laos, drove to the Fresno City College campus looking for his intended bride. Locating her at her job in the student finance office, he spirited her away to his cousin’s house.

"Kong Moua called it zij poj niam, or “marriage by capture,” in his culture an accepted form of matrimony akin to elopement.

"However, his “bride,” also a Hmong but more assimilated into American culture, called it kidnaping and rape. She also called the police.

"Kong Moua’s lawyer, in negotiating a plea to the lesser charge of false imprisonment, introduced literature documenting the Hmong marital customs.

"After reading the material, the judge sentenced Kong Moua to 120 days in jail and fined him $1,000, with $900 of that going to the victim as reparations--far less than the state prison term he could have gotten for kidnaping and rape.


"In another Hmong “marriage by capture” case, this one in St. Paul, Minn., Ramsey County Assistant Attorney Daniel Hollihan, decided not to take the case to trial.

"With the help of St. Paul’s Southeast Asian Refugee Study Project, Hollihan learned that in the Hmong “marriage by capture,” the woman or girl, often under 15 years of age, must protest her capture by insisting “No, no, I am not ready” to be considered virtuous and desirable. If the man does not take her by the hand and lead her off to his own home, he is considered too weak to be a husband.

"The prosecutor decided that it would be almost impossible to convince a jury that the girl really meant “no” and had been taken away against her will and raped. So he opted for a plea bargain.

“I went to the victim’s family and said, ‘How would you resolve this in the old country?’ ” Hollihan said.

“The victim’s aunt, who spoke English, told me $3,000 and no jail, $2,000 and 60 days, or $1,000 and 90 days, to restore the family honor and pride,” he said.

"The defendant was allowed to plead guilty to sexual intercourse with a child under the age of 12, and fined $1,000 with no jail time."

Sunday, September 5, 2021

Australia and England swap millions of vaccine doses

Barter can increase efficiency. The Financial Times has the story:

Australia strikes deal to ‘swap’ 4m vaccine doses with UK  by William Langley and Oliver Barnes 

"The UK will send 4m Covid-19 vaccine doses to Australia in a swap deal aimed at accelerating Canberra’s stuttering rollout and bolstering British supplies later in the year when ministers are pushing for a booster campaign. 

"The first batch of 292,000 BioNTech/Pfizer doses will arrive in Australia in the coming days, with the remainder due by the end of the month, Prime Minister Scott Morrison said on Friday. 

"Australia will return an equivalent 4m doses before the end of the year, according to the UK health department.

"The deal is designed to speed up Australia’s vaccination rollout, which has been one of the slowest in the world, and Morrison said it would allow the government to bring forward its prospective reopening date.

"It reflects the UK’s calculation that it does not currently need all its stockpiled doses, which expire in a matter of months if not used, while allowing London to boost supplies later this year in anticipation of a broad booster campaign and the vaccination of 12 to 15-year-olds."