Stability vs. No Justified Envy, by Romm, Roth and Shorrer

 Here's a recent paper that clarifies some of the prior literature on comparing stability in two-sided matching with a related kind of envy-freeness in allocations of goods to individuals using priorities.

Romm, Assaf, Alvin E. Roth, and Ran I. Shorrer, "Stability vs. No Justified Envy," Games and Economic Behavior, Volume 148, November 2024, Pages 357-366  https://doi.org/10.1016/j.geb.2024.10.002
 
Abstract: Stability and “no justified envy” are used almost synonymously in the matching theory literature. However, they are conceptually different and have logically separate properties. We generalize the definition of justified envy to environments with arbitrary school preferences, feasibility constraints, and contracts, and show that stable allocations may admit justified envy. When choice functions are substitutable, the outcome of the deferred acceptance algorithm is both stable and admits no justified envy.

Kim Krawiec interview about WHO demands for national self sufficiency in blood donation and kidney exchange

 The University of Virginia takes note of the recent Krawiec & Roth paper I blogged about in August.

Here is their interview with Kim about the paper:

WHO Stifles International Blood and Organ Donations, Argue Professors. Professor Kimberly Krawiec, Nobel Prize Winner Alvin E. Roth of Stanford Argue World Health Organization Policies Need Revision

Here are the first two Q&As

"What motivated you to critique the WHO principles of self-sufficiency and nonremuneration in organs and blood? ​

"The severe shortage of both blood products and transplantable organs, especially kidneys, was our motivation and has motivated much of our other work, both together and separately. In the United States alone, the organ transplant waiting list is approximately 100,000 people, and if current trends continue, it will only grow in the coming years.

"Shortages of blood products present a similar challenge. Although wealthy countries are typically able to satisfy domestic whole blood needs, the vast majority of low- and middle-income countries (LMIC) are not. As a result, in many LMIC, shortages of blood for transfusion contribute to maternal death, death from traffic accidents and complications from childhood anemia. Moreover, even wealthy countries experience seasonal shortages of whole blood or deficiencies in some blood components, such as platelets, which are harder to collect and have a shorter shelf life.

The shortage of plasma-derived medicinal products (PDMPs) is particularly severe and entirely preventable. PDMPs are life-saving treatments for multiple acute and chronic conditions for which there are no alternative treatments. Yet these life-saving therapies are unavailable to much of the world’s population. The United States, one of the few countries to pay plasma donors, supplies 70% of the world’s plasma needs, with Germany, Austria, Hungary, Czechia and Latvia (which also permit some form of payment for plasma donors) supplying another 20% of the world total. In other words, a handful of countries supply plasma to the rest of the world, including other wealthy countries. Meanwhile, LMIC who can neither collect and process their own nor afford to purchase blood products on the open market (or are prevented from doing so under the terms of the foreign aid that supports their health system) simply do without, to the detriment of their citizens.

"How do current WHO policies on organ and blood donation contribute to this problem?

"WHO policy mandates both national (or sometimes only regional) self-sufficiency and an absence of remuneration for both blood products and transplantable organs — what we refer to in the paper as “the twin principles.” These twin principles are unhelpful separately and unworkable together. Their effect on blood products is particularly stark — no country that fails to compensate donors is self-sufficient in plasma collection and few LMIC collect sufficient supplies of whole blood.

"The self-sufficiency mandate presents a real hurdle to progress in transplantation, especially for smaller countries and LMIC. This is especially the case because some of the most exciting and promising developments for increasing the availability of transplants have been in kidney exchange, a mechanism that leverages in-kind exchange, rather than financial compensation, to encourage and facilitate donation among those with willing but incompatible partners. But kidney exchange works best when a large pool of patient-donor pairs can engage with one another. So, requiring that transplantation be contained within national boundaries unnecessarily limits access to transplants that could be achieved only by cross-border exchange."

Many preference signals as a soft cap on number of applications in medical residency matching

 Here's a review article on matching for medical residents,  with particular attention to neurosurgery, in the Cureus Journal of Medical Science.  In specialties that (like neurosurgery) allow applicants to send many signals, many applicants signal to and match with programs with which they have some prior connection.

Ozair, Ahmad, Jacob T. Hanson, Donald K. Detchou, Matthew P. Blackwell, Abigail Jenkins, Marianne I. Tissot, Umaru Barrie et al. "Program Signaling and Geographic Preferences in the United States Residency Match for Neurosurgery." Cureus 16, no. 9 (2024).

Abstract: Postgraduate residency training has long been the cornerstone of academic medicine in the United States. The Electronic Residency Application Service (ERAS), managed by the Association of American Medical Colleges (AAMC), is the central residency application platform in the United States for most clinical specialties, with the National Residency Matching Program (NRMP) being the algorithm for matching residency programs with applicants. However, the determination of the best fit between ERAS applicants and programs has been increasingly challenged by the rising number of applicants per residency spot. This application overburdening across competitive specialties led to several adverse downstream effects, which affected all stakeholders. While several changes and proposals were made to rectify the issue of application overburdening, the 2020-2021 ERAS Match Cycle finally saw several competitive specialties, including otolaryngology and urology, utilize a new system of supplemental residency application based on preference signals/tokens. These tokens permit applicants to electronically signal a select number of programs in a specialty of choice, with the program reviewing the application now cognizant that they have been signaled, i.e., the applicant has chosen to use up a limited set of signals for their program. Initial results from otolaryngology and urology, as described in this article, indicated the value of this new system to both applicants and educators. Given the favorable outcomes and broader uptake of the system among other specialties, the field of neurosurgery adopted the utilization of the ERAS-based program signaling and geographic preference for the first time for the 2022-2023 Residency Application Cycle and later opted to continue them for the 2023-2024 and 2024-2025 cycles. For the 2024-2025 Match Cycle, neurosurgery applicants have 25 signals, i.e., a "high-signal" approach, where non-signaled programs have a low interview conversion rate. This literature review discusses the rationale behind the change, the outcomes of other competitive specialties from prior cycles, the evolving nature of the change, and the potential impact on applicants and programs. As we describe in this review, signaling may potentially represent a surrogate form of an application cap. Other considerations relate to cost savings for both applicants and programs from a high-signal approach in neurosurgery. These modifications represent a foundational attempt to alleviate the application overburdening and non-holistic review in the residency application process, including for neurosurgery. While these changes have been a welcomed addition for all stakeholders in residency match cycles so far, further prospectively directed surveys along with qualitative research studies are warranted to better delineate the downstream impact of these changes and guide further optimization of the application system.

A 40 year old proof about top trading cycles is corrected (by two Berkeley grad students)

 Science (and math) can be self-correcting, sometimes slowly.  Here's an article that corrects the first proof that the top trading cycles algorithm is group strategy proof.  That's a true result, with multiple subsequent proofs.  But apparently the first proof presented wasn't the best one.  That's good to know.

One reason this may have taken a long time to spot is that the result is correct, and that there are subsequent proofs that connect the result to properties of other mechanisms.  

Will Sandholtz and Andrew Tai, the authors, did this work as Ph.D. students at UC Berkeley. (good for them!)

Group incentive compatibility in a market with indivisible goods: A comment  by Will Sandholtz and Andrew Tai

"Highlights

• Bird (1984), first to show top trading cycles is group strategy-proof, has errors.

•We present corrected results and proofs.

•We present a novel proof of strong group strategy-proofness without non-bossiness.

"Abstract: We note that the proofs of Bird (1984), the first to show group strategy-proofness of top trading cycles (TTC), require correction. We provide a counterexample to a critical claim and present corrected proofs in the spirit of the originals. We also present a novel proof of strong group strategy-proofness using the corrected results."

More on non-anonymous kidney exchange in India

 Here's some further description of how kidney exchange is conducted in India without authorization* to use nondirected donors (so that all exchanges are conducted in cycles, i.e. in the absence of chains of exchange).

Vivek B. Kute, Himanshu V Patel, Subho Banerjee,Divyesh P Engineer, Ruchir B Dave, Nauka Shah, Sanshriti Chauhan ,Harishankar Meshram , Priyash Tambi  , Akash Shah, Khushboo Saxena,Manish Balwani , Vishal Parmar, Shivam Shah, Ved Prakash ,Sudeep Patel, Dev Patel, Sudeep Desai, Jamal Rizvi , Harsh Patel, Beena Parikh, Kamal Kanodia, Shruti Gandhi, Michael A Rees,  Alvin E Roth,  Pranjal Modi “Impact of single centre kidney-exchange transplantation to increase living donor pool in India: A cohort study involving non-anonymous allocation,”Nephrology, September 2024, https://onlinelibrary.wiley.com/doi/10.1111/nep.14380  

"In India, 85% of organ donations are from living donors and 15% are from deceased donors. One-third of living donors were rejected because of ABO or HLA incompatibility. Kidney exchange transplantation (KET) is a cost-effective and legal strategy to increase living donor kidney transplantation (LDKT) by 25%–35%.

"3.3 Non-anonymous allocation

"The THOA*, which regulates KET in India, is silent on the need for anonymity, so there is no legal requirement for anonymity in India, as compared with other countries, such as the Netherlands and Sweden. Our experience was that 90% of iDRP [incompatible Donor-Recipient Pairs] requested the opportunity to meet their matched donor and recipient pair (mDRP) and 10% asked the treating physician to decide if they should meet. None of the iDRP requested anonymity. Therefore, we have practiced absolute non-anonymity, meaning that all mDRPs meet and share medical reports after a potential exchange is identified, but before the formal allocation of pairs. If an iDRP requests anonymity, we would be willing to accommodate them, but to date, none have done so.

"Upon meeting with their mDRP, the iDRP can refuse the proposed exchange option without reason and continue to be on the waitlist and active in the KET pool. iDRPs must complete transplant fitness and legal documents required for transplant permission from the health authority before they are given the opportunity to meet their mDRP. A meeting between mDRPs occurs in the presence of a transplant physician, who can help solve any query before the proposed match is accepted by the involved pairs. iDRP are introduced to their mDRP prior to scheduling transplants to avoid chain collapse due to iDRP refusal of the mDRP. The mDRP shares medical reports of donors with each other, can also discuss with their other family members, and consults with their family physician/nephrologist before deciding whether to proceed. Living kidney donors are fully informed of perioperative and long-term risks before making their decision to donate. In India, donor age group matching is most commonly expected for all iDRP in the KAS."

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Earlier:

Monday, September 18, 2023

Kidney Paired Donation in Developing Countries: a Global Perspective

*Here's the THOA, THE TRANSPLANTATION OF HUMAN ORGANS AND TISSUES ACT, 1994

Simulating kidney exchange policies in Germany

 Here are a set of simulations designed to help Germany establish a national (rather than a fragmented) kidney exchange system.

Itai Ashlagi, Ágnes Cseh, David Manlove, Axel Ockenfels & William Pettersson,  Designing a kidney exchange program in Germany: simulations and recommendations. Central European Journal of Operations Research  (2024). https://doi.org/10.1007/s10100-024-00933-0

"Abstract: We examine some of the opportunities and challenges concerned with establishing a centralized national kidney exchange program in Germany. Despite the many advantages of a national program, without deliberate design and policy intervention, a fragmented kidney exchange program may emerge. We study a number of collaboration strategies, and resulting simulations suggest that transplant centers may find it advantageous not to fully participate, resulting in a net reduction in the number of transplants. These results also suggest that allowing more forms of kidney exchange, such as three-way exchanges and non-directed donations, can significantly increase the number of transplants while making participation in a national program more attractive and thus national coordination and cooperation more robust. We propose a multi-level policy approach that is easy to implement and would promote an efficient German kidney exchange program that benefits recipients, donors and hospitals."

...

The concluding sentence of the paper is:

"Germany should establish a robust, well-functioning national KEP that can be easily and straightforwardly integrated into an international KEP."

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Background:

Thursday, July 18, 2024

Kidney exchange in Germany: draft of a proposed law

Incentives matter for getting participation in clinical trials by low income households

 Here's a study that casts some light (via a randomized experiment) on the importance of incentives to get representative participation in clinical trials.

Nonrepresentativeness in Population Health Research: Evidence from a COVID-19 Antibody Study By Deniz Dutz, Michael Greenstone, Ali Hortaçsu, Santiago Lacouture, Magne Mogstad, Azeem M. Shaikh, Alexander Torgovitsky, and Winnie van Dijk, AER: Insights 2024, 6(3): 313–323, https://doi.org/10.1257/aeri.20230195

Abstract: "We analyze representativeness in a COVID-19 serological study with randomized participation incentives. We find large participation gaps by race and income when incentives are lower. High incentives increase participation rates for all groups but increase them more among underrepresented groups. High incentives restore representativeness on race and income and also on health variables likely to be correlated with seropositivity, such as the uninsured rate, hospitalization rates, and an aggregate COVID-19 risk index."

"We analyze representativeness in a unique COVID-19 serological study. Unlike most studies, the Representative Community Survey Project (RECOVER)COVID-19 serological study experimentally varied financial incentives for participation. The study was conducted on households in Chicago (the target population). Randomly sampled households were sent a package that contained a self-administered blood sample collection kit and were asked to return the sample by mail to be tested for the presence of COVID-19 antibodies (“seropositivity”). Households in the sample were randomly assigned one of three levels of financial compensation for participating in the study: $0, $100, or $500.

"We find that households in neighborhoods with high shares of minority and poor households are grossly underrepresented at lower incentive levels. High incentives increase participation rates for all groups but increase them more among underrepresented groups. A $500 incentive restores representativeness in terms of neighborhood-level race and poverty status. Representativeness is also restored in health variables likely to be correlated with seropositivity, such as the uninsured rate, hospitalization rates, and an aggregate COVID-19 risk index. Since incentives were randomly assigned and only revealed after the household was contacted, the noncontact rates at $0 and $100 should be the same as at $500, implying that differential hesitancy to participate is responsible for much of the nonrepresentativeness that we find at lower incentives.

"We are not aware of studies that randomize financial incentives in population health studies. It is well appreciated that racial minorities and lower-income households participate in health research at lower rates.1  The impact of incentives on survey participation rates conditional on demographic characteristics has been studied in the survey methodology literature (see Groves et al. 2009; Singer and Ye 2013, and references therein). The incentives used in this literature are typically an order of magnitude smaller than the incentives in the RECOVER study."

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Some earlier related posts:

Monday, February 22, 2021

Ethical Payment in Human Infection Challenge Studies in the American Journal of Bioethics

Monday, March 1, 2021

Compensating challenge vaccine trial participants: further discussion in the American Journal of Bioethics

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.) "

Sunday, November 1, 2020

What do we know about the effects of payments to participants in challenge trials for vaccines, and other public spirited activities?

WHO Says Countries Should Be Self-Sufficient In (Unremunerated) Organs And Blood, by Krawiec and Roth

 Requiring national self sufficiency in blood and plasma supplies is particularly hard on low and middle income countries, as is limiting the possibility of participating in active kidney exchange programs.

WHO Says Countries Should Be Self-Sufficient In (Unremunerated) Organs And Blood by Kimberly D. Krawiec and Alvin E. Roth : August 24, 2024,   Available at SSRN: https://ssrn.com/abstract=4935827

Abstract: This chapter critiques the twin World Health Organization (WHO) principles of self-sufficiency and nonremuneration in organs and blood, urging a more sensible approach to the scarce resources of blood products and transplantable organs. WHO and other experts have failed to acknowledge the tension between self-sufficiency and nonremuneration in blood products--no country that fails to pay plasma donors is self-sufficient. Furthermore, international cooperation and cross-border transplantation provide numerous benefits, especially in smaller countries and those without well-developed domestic exchange programs. The combination of these twin principles denies to health care many of the benefits that trade has brought to so many other human endeavors and the effects are particularly damaging to low and middle income countries. Substances of human origin are special, but not so special that we prohibit plasma or organ donation. We should be open to exploring and experimenting with ways to bring to health care some of the benefits that trade has brought to so many other human endeavors, such as the production and distribution of food and lifesaving vaccines and other medicines.

Here's the concluding paragraph:

"We close by noting that the combination of the nonremuneration principle and the self-sufficiency principle deny to health care many of the benefits that trade has brought to so many other human endeavors. Substances of human origin are special, but not so special that we prohibit plasma or organ donation. So we should be open to exploring and experimenting with ways to bring to health care some of the benefits that trade has brought to so many other human endeavors, such as the production and distribution of food and lifesaving vaccines and other medicines."

Crowding in School Choice, By William Phan, Ryan Tierney, and Yu Zhou

 Here's an innovative paper in the latest AER.

The authors use North Carolina's Wake County Public School System as a motivating example of crowding and the information available to parents about crowding.

Crowding in School Choice, By William Phan, Ryan Tierney, and Yu Zhou, American Economic Review 2024, 114(8): 2526–2552, https://doi.org/10.1257/aer.20220626

Abstract: "We consider the market design problem of matching students to schools in the presence of crowding effects. These effects are salient in parents’ decision-making and the empirical literature; however, they cause difficulties in the design of satisfactory mechanisms and, as such, are not currently considered. We propose a new framework and an equilibrium notion that accommodates crowding, no-envy, and respect for priorities. The equilibrium has a student-optimal element that induces an incentive-compatible mechanism and is implementable via a novel algorithm. Moreover, analogs of fundamental structural results of the matching literature (the rural hospitals theorem, welfare lattice, etc.) survive."

"In our model, each student has a preference over the two dimensions of school identity and the total amount of educational resources that they consume at each school. The more crowded a school is, the fewer resources each student enjoys, and so the value of this second dimension at each school will emerge endogenously. 

...

"We propose a new equilibrium concept: rationing crowding equilibrium (RCE). The core of our innovation is in realizing that the vector of resource levels can function like a price. Consider a competitive solution applied in our context. We may imagine that an auctioneer announces a resource vector, which then determines a (finite) list of school and resource-level pairs. Each student will then demand (generically) one of these pairs, and we can ask the usual market clearing question: Does there exist a resource vector at which, for each school, the demand for educational resources is equal to its supply? We show that the answer is yes, if we allow for an error of at most one seat.9,10 Since each student faced the same budget set, the resulting allocation satisfies no-envy, at least for schools that have not reached their enrollment cap

An Experimental Study of the Chinese Organ Allocation System

 China presently has a low rate of organ donations per million population, so there's a lot of room for growth.  Here's a study suggesting that giving priority on the waiting list to family members of donors could help (as it has done in Israel):

Li, Danyang, Luo, Jun, Ye, Hang and Zheng, Heng. "Is Family-Priority Rule the Right Path? An Experimental Study of the Chinese Organ Allocation System" The B.E. Journal of Economic Analysis & Policy, vol. 24, no. 3, 2024, pp. 929-964. https://doi-org.stanford.idm.oclc.org/10.1515/bejeap-2023-0213

Abstract: China is experiencing an organ shortage crisis. We experimentally test the effectiveness of the family-priority allocation rule on organ donation and argue that such incentive would be highly motivating in Chinese family-oriented culture. Results of our experiment show that introducing the family-priority rule can not only increase donor registration but also promote family consent. Such priority rule would be particularly effective to increase deceased organ donation in China, as it will significantly promote donor registration and meanwhile generate a consistent higher family consent rate in a more family-orientated culture.

Performance Feedback and Organ Donor Registrations, by House, Lacetera, Macis, and Mazar.

 When you register for a driver's license in the U.S., you fill out a form that has an opportunity to register as an organ donor. Did the clerk who accepts your form ask you if you had checked the box?  Would it help if he/she got feedback on how many organ donor registrations she had facilitated?

Here's an experiment about the equivalent interaction in Canada, where "most of the organ donor registrations in Ontario (pre-Covid-19 pandemic: 85 %) occurred during in-person visits to ServiceOntario centers (Trillium Gift of Life, 2017), which through their customer service representatives (CSRs) provide a wide range of services to residents ranging from issuing driver and vehicle licensing to public health insurance registration and business licensing."

House, Julian, Nicola Lacetera, Mario Macis, and Nina Mazar. "Nudging the Nudger: Performance Feedback and Organ Donor Registrations." Journal of Health Economics (2024): 102914.

"Abstract: In a randomized controlled trial conducted in three waves over 2.5 years and involving nearly 700 customer-service representatives (CSRs) from a Canadian government service agency, we studied how providing CSRs with repeated performance feedback, with or without peer comparison, affected their subsequent organ donor registration rates. The feedback resulted in a 25 % increase in daily signups compared to otherwise equivalent encouragements and reminders. Adding benchmark information about peer performance did not amplify or diminish this effect. We observed increased registration rates for both high and low performers. A post-intervention survey indicates that CSRs in all conditions found the information included in the treatments helpful and motivating, and that signing up organ donors makes their job more meaningful. We also found suggestive evidence that performance feedback with benchmark information was the most motivating and created the least pressure to perform."

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Related post:

Monday, July 22, 2024

Don't take "No" for an answer in deceased organ donor registration (a paper forthcoming after ten+ years)

Knights and Knaves reimagined by Jacob Glazer and Ariel Rubinstein

 Knights and Knaves are a venerable class of logical puzzles in which knights always tell the truth and knaves always lie, and the task is to think of a way to interrogate a knight or knave to learn the truth about something.  Here's a paper by Glazer and Rubinstein that looks like it opens a new vista of such problems (but don't trust me, I could be a knave...)

Magical Implementation by Jacob Glazer and Ariel Rubinstein, July 21, 2024

"Abstract: A principal would like to decide which of two parties deserves a prize. Each party privately observes the state of nature that determines which of them deserves the prize. The principal presents each party with a text that truthfully describes the conditions for deserving the prize and asks each of them what the state of nature is. The parties can cheat but the principal knows their cheating procedure. The principal “magically implements” his goal if he can come up with a pair of texts satisfying that in any dispute, he will recognize the cheater by applying the “honest-cheater asymmetry principle”. According to this principle, the truth is with the party satisfying that if his statement is true, then the other party (using the given cheating procedure) could have cheated and made the statement he is making, but not the other way around. Examples are presented to illustrate the concept."

Before getting technical, the paper begins with this delightful example.

"Two invigilators, A and B, have witnessed a student receiving a whispered message from another student during an exam. The invigilators have not seen the questions on the exam but would be able to solve them. It is known that A does not like the student who received the message while B does. The exam includes multiple questions but only one refers to the variable α and reads as follows: “Solve the equation α + 1 = 4.” The student answers the question correctly. Invigilator A claims that the whispered message was: “α = 3.” This is a serious allegation and if correct, the student’s exam will be disqualified. Invigilator B claims that the whispered message was: “Solve the equation α+1 = 4 first.” If he is right, then the student’s answer genuinely reflects his knowledge of the material and there will not be any serious consequences. Who should be believed: A or B?

"Although there is no definitive proof one way or the other, we would choose to believe B. The reasoning would be that if the message was “Solve the equation α + 1 = 4 first”, then A (who dislikes the student) could solve the equation himself and claim that the message was “α = 3”. On the other hand, if the message was “α = 3” it is very unlikely that B (who likes the student and who, as mentioned, has not seen the exam questions) could guess that the equation to be solved is α+1 = 4 rather than any other equation with the same solution. Hence, there is an asymmetry between the two conflicting claims which makes it possible to reasonably conclude that B’s claim is the truthful one."

Don't take "No" for an answer in deceased organ donor registration (a paper forthcoming after ten+ years)

 Here's a paper reporting a "field in the lab" experiment with actual organ donor registrations, that took over ten years to get published (after considerable revision and additional data collection).  But it has an important message for how to ask people to agree to donate their organs after they die, should they happen to be among those rare cases in which deceased organs can be donated.  The paper has two messages: one is that it doesn't increase donor registration to ask people to answer 'yes' or 'no', compared to just asking if they want to register at this time.  The second message is that people who have declined to register as a donor in the past may agree if asked again (so, don't take "no" for a final answer).

Here's the pre-publication version that will appear in AEJ:Policy.

Increasing Organ Donor Registration as a Means to Increase Transplantation: An Experiment With Actual Organ Donor Registrations  by Judd B. Kessler and Alvin E. Roth, AMERICAN ECONOMIC JOURNAL: ECONOMIC POLICY (FORTHCOMING)

Abstract: The U.S. has a severe shortage of organs for transplant. Recently — inspired by research based on hypothetical choices — jurisdictions have tried to increase organ donor registrations by changing how the registration question is asked. We evaluate these changes with a novel “field-in-the-lab” experiment, in which subjects change their real organ donor status, and with new donor registration data collected from U.S. states. A “yes/no” frame is not more effective than an “opt-in” frame, contradicting conclusions based on hypothetical choices, but other question wording can matter and asking individuals to reconsider their donor status increases registrations.

And here's the blog post about and link to the 2014 NBER working paper (which was itself a revision of an earlier version), and some of the press coverage it received at the time:

Tuesday, September 2, 2014

Don't take "No" for an answer: a reconsideration of how to do deceased donor registration

Signaling for medical residencies: the first few years

Two papers report on signaling in Otolaryngology and Orthopaedic surgery.

 The Otolaryngology societies have a summary of the current state of affairs that's worth hearing. A number of specialties (including Oto) allow many signals, and these seem to be acting as a soft cap on applications, rather than as a signal of special interest as in specialties that (like Economics) allow only a small number of signals.

Preference Signaling in Otolaryngology—Past, Present, and Future: A Comment From the Society of University Otolaryngologists (SUO), Association of Academic Departments in Otolaryngology (AADO), and the Otolaryngology Program Directors Organization (OPDO)  by Steven D. Pletcher MD, Bradley F. Marple MD, David J. Brown MD, The Laryngoscope Early View,  First published: 04 July 2024  https://doi.org/10.1002/lary.31613

"The year 2020 was a year of change. The residency application process, already suffering from spiraling application numbers,1 now faced the COVID-19 pandemic with a loss of away rotations and apprehension about virtual interviews. In the face of change, the Otolaryngology Program Directors Organization Council (OPDO) approached the leadership of the Association of Academic Departments in Otolaryngology (AADO) and the Society of University Otolaryngologists (SUO) with a recommendation to implement preference signaling. This system, originally described in the economics PhD marketplace,2 allows students a set number of signals (Otolaryngology used 5 in its inaugural year) to send to programs of particular interest. 

...

"Following the lead of Otolaryngology, Urology, General Surgery, Internal Medicine, and Dermatology implemented preference signaling the following year. Since that time, signaling has grown exponentially and is now utilized in the residency application process of nearly every specialty. 

...

"In the 2024-2025 residency application cycle, the evolution of preference signaling continues. Building on Otolaryngology's experience, in the 2023 application cycle Orthopaedic Surgery implemented a high-signal approach, providing applicants with 30 signals. This transition shows promise for reversing the vexing problem of spiraling application numbers—“Big Signaling” has now been adopted by Otolaryngology and four additional specialties the majority of whom have shown a 25%–30% decrease in applications submitted per student saving students a combined $2.5 million in application fees alone. Obstetrics and Gynecology has piloted a tiered signaling system, providing three gold and 15 silver signals to their students. 

...

"Because the number of signals received by programs is not publicized, students are unable to reliably target programs where their signals are less likely to be diluted by competing signals. Specialties should consider providing voluntary “signal cohort” (i.e., my program received between 75 and 100 signals in the 2024 application cycle) data to help applicants make more informed signal decisions and programs with low signal numbers will likely attract additional candidates. 

...

"One of the key statistics to guide applicants in high signal specialties is the interview offer rate for non-signal applications: this helps define the value of applications beyond the set number of signals."

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Preference Signaling in the Orthopaedic Surgery Match: Applicant and Residency Program Attitudes, Behaviors, and Outcomes, by Guthrie, Stuart Trent MD, FAOA1,a; Dagher, Tanios BSE2; Essey-Stapleton, Jodi MS, MEd3; Balach, Tessa MD, FAOA2,  JBJS Open Access 9(2):e23.00146, April-June 2024. | DOI: 10.2106/JBJS.OA.23.00146

"In the first year of preference signaling, applicants reported applying to 16% fewer programs than if preference signaling had not been available. These results align with AAMC data, which report applications per program dropping 17.4% (from an average of 639.6 to 774.6), and applications per applicant dropping to 76.9 from 86.07,8. Further changes could occur in future cycles as students become more accustomed to the influence of signaling on their application."

The Morality of Markets, by Mathias Dewatripont and Jean Tirole, in the JPE

 Are markets moral, immoral, or amoral?  Here's a new entry to that argument.

The Morality of Markets, by Mathias Dewatripont and Jean Tirole, Journal of Political Economy, online ahead of print.

Abstract: "Scholars and civil society have argued that competition erodes supplier morality. This paper establishes a robust irrelevance result, whereby intense market competition does not crowd out consequentialist ethics; it thereby issues a strong warning against the wholesale moral condemnation of markets and procompetitive institutions. Intense competition, while not altering the behavior of profitable suppliers, may, however, reduce the standards of highly ethical suppliers or not-for-profits, raising the potential need to protect the latter in the marketplace."

"The irrelevance result.—We ask: does the combination of unethical (or, more generally, UPI [unethical/present biased/influenceable]) consumers and of suppliers with consequentialist social preferences imply that moral behavior deteriorates under more intense competition? Our answer to this question is no. Indeed, under weak assumptions, the degree of competitive pressure is irrelevant to ethical behavior (moral choices are independent of demand functions) if prices are flexible.

"The intuition behind the irrelevance result goes as follows: when a supplier faces more intense competition (a more elastic demand), raising ethical behavior has a bigger negative impact on the supplier’s market share and is therefore costlier for the supplier; ceteris paribus, this makes suppliers cut ethical corners in reaction to the increase in competition, as indicated in the conventional wisdom. However, next to this first market share effect, there is a second reduced-stakes effect: a more intense competition reduces prices and markups, making supplier ethical concerns loom larger relative to material ones. We show that a sufficient condition for these two effects to exactly offset each other is that suppliers have consequentialist preferences and returns to scale are constant.

"The irrelevance result, which applies as well to ethical or indifferent consumers, is important not only because it sheds light on the validity of the widespread concern about markets expressed by the public opinion, social scientists, politicians, and religious leaders but also because it affects our stance vis-à-vis key competition-enhancing public policies, such as the opening of borders to free trade, competition policy, and the deregulation of industries. The irrelevance result is also in stark contrast with earlier theoretical results on the irrelevance of social preferences in highly competitive environments, in particular, with Dufwenberg et al. (2011) and Sobel (2015): in our case, the social preferences of suppliers and of consumers matter regardless of the competitive pressure, and it is the intensity of competition that is irrelevant. The difference is driven in particular by the fact that in their settings, one can affect others’ utilities only through one’s impact on their quantities traded or the market price, an impact that vanishes under perfect competition. In our setting, an individual may want to change her action just because it is objectionable to herself or others, even if this does not affect their ability to trade, a feature that is widespread in the real world. See the literature review for a detailed comparison."

A proposal to assess public opinion in Europe on compensation for organ donors

 Here's a paper that proposes doing an experiment. Concerning compensation for organ donors. In Europe.  With the hope of influencing policy and reducing the shortage of transplants.  (A very worthy cause, that brings to mind Titian's painting of Sisyphus...)

Ambagtsheer, Frederike, Eline Bunnik, Liset HM Pengel, Marlies EJ Reinders, Julio J. Elias, Nicola Lacetera, and Mario Macis. "Public Opinions on Removing Disincentives and Introducing Incentives for Organ Donation: Proposing a European Research Agenda." Transplant International 37 (2024): 12483.

Abstract: The shortage of organs for transplantations is increasing in Europe as well as globally. Many initiatives to the organ shortage, such as opt-out systems for deceased donation and expanding living donation, have been insufficient to meet the rising demand for organs. In recurrent discussions on how to reduce organ shortage, financial incentives and removal of disincentives, have been proposed to stimulate living organ donation and increase the pool of available donor organs. It is important to understand not only the ethical acceptability of (dis)incentives for organ donation, but also its societal acceptance. In this review, we propose a research agenda to help guide future empirical studies on public preferences in Europe towards the removal of disincentives and introduction of incentives for organ donation. We first present a systematic literature review on public opinions concerning (financial) (dis)incentives for organ donation in European countries. Next, we describe the results of a randomized survey experiment conducted in the United States. This experiment is crucial because it suggests that societal support for incentivizing organ donation depends on the specific features and institutional design of the proposed incentive scheme. We conclude by proposing this experiment’s framework as a blueprint for European research on this topic.

Fairness, efficiency and strategy proofness in assigning indivisible objects: two new papers

 Here are two new papers on the burgeoning literature of matching people to scarce indivisible resources.

First, an experiment by Claudia Cerrone, Yoan Hermstrüwer,  and Onur Kesten.

Claudia Cerrone, Yoan Hermstrüwer, Onur Kesten, School Choice with Consent: an Experiment, The Economic Journal, Volume 134, Issue 661, July 2024, Pages 1760–1805,   https://doi.org/10.1093/ej/uead120

Abstract: Public school choice often yields student assignments that are neither fair nor efficient. The efficiency-adjusted deferred acceptance mechanism allows students to consent to waive priorities that have no effect on their assignments. A burgeoning recent literature places the efficiency-adjusted deferred acceptance mechanism at the centre of the trade-off between efficiency and fairness in school choice. Meanwhile, the Flemish Ministry of Education has taken the first steps to implement this algorithm in Belgium. We provide the first experimental evidence on the performance of the efficiency-adjusted deferred acceptance mechanism against the celebrated deferred acceptance mechanism. We find that both efficiency and truth-telling rates are higher under the efficiency-adjusted deferred acceptance mechanism than under the deferred acceptance mechanism, even though the efficiency-adjusted deferred acceptance mechanism is not strategy proof. When the priority waiver is enforced, efficiency further increases, while truth-telling rates decrease relative to variants of the efficiency-adjusted deferred acceptance mechanism where students can dodge the waiver. Our results challenge the importance of strategy proofness as a prerequisite for truth telling and portend a new trade-off between efficiency and vulnerability to preference manipulation.

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And here's a theoretical paper by Xiang Han (韩翔)

Xiang Han, On the efficiency and fairness of deferred acceptance with single tie-breaking, Journal of Economic Theory, Volume 218, 2024, https://doi.org/10.1016/j.jet.2024.105842. (https://www.sciencedirect.com/science/article/pii/S0022053124000486)

Abstract: As a random allocation rule for indivisible object allocation under weak priorities, deferred acceptance with single tie-breaking (DA-STB) is not ex-post constrained efficient. We first observe that it also fails to satisfy equal-top fairness, which requires that two agents be assigned their common top choice with equal probability if they have equal priority for it. Then, it is shown that DA-STB is ex-post constrained efficient, if and only if it is equal-top fair, if and only if the priority structure satisfies a certain acyclic condition. We further characterize the priority structures under which DA-STB is ex-post stable-and-efficient. Based on the characterized priority domains, and using a weak fairness notion called local envy-freeness, new theoretical support is provided for the use of this rule: for any priority structure, among the class of strategy-proof, ex-post stable, symmetric, and locally envy-free rules, each of the above desiderata—ex-post constrained efficiency, ex-post stability-and-efficiency, and equal-top fairness—can be achieved if and only if it can be achieved by DA-STB.

Centralized assignment mechanisms that don't include all the relevant choices, by Kapor, Karnani and Neilson in the JPE

 One of the issues in organizing a centralized matching mechanism is to make the market thick, by including all or most of the relevant choices in the centralized system.  If not, there will be transactions outside of the centralized marketplace, and some of them may be costly to the system.

Here's a paper that explores that in the context of  college admissions in Chile.

Aftermarket Frictions and the Cost of Off-Platform Options in Centralized Assignment Mechanisms, by Adam Kapor, Mohit Karnani, and Christopher Neilson, Journal of Political Economy, forthcoming.

Abstract: "We study the welfare and human capital impacts of colleges’ (non)participation in Chile’s centralized higher-education platform, leveraging administrative data and two policy changes: the introduction of a large scholarship program and the inclusion of additional institutions, which raised the number of on-platform slots by approximately 40%. We first show that the expansion of the platform raised on-time graduation rates. We then develop and estimate a model of college applications, offers, wait lists, matriculation, and graduation. When the platform expands, welfare increases, and welfare, enrollment, and graduation rates are less sensitive to off-platform frictions. Gains are larger for students from lower-socioeconomic-status backgrounds."

"in virtually every practical implementation there exist many off-platform options that are available to participants of the match. In primary and secondary education, these include private schools or charter schools that do not participate in the centralized system. In other cases, such as higher education, some providers may be excluded from the platform by regulation, while others may choose not to participate. When off-platform options exist, applicants may renege on their assigned matches in favor of programs that did not participate in the centralized process. In turn, these decisions lead to the use of wait lists and aftermarkets, which may be inefficient due to the presence of congestion and matching frictions and can be inequitable if some students are better able to navigate this partially decentralized process, negating some of the benefits of the match.

"In this paper, we study the empirical relevance of the configuration of on- and off-platform options for students’ welfare and for persistence and graduation in higher-education programs. We document the importance of negative externalities generated by off-platform options and quantify a measure of aftermarket frictions that contribute to generating them in practice. Our empirical application uses data from the centralized assignment system for higher education in Chile, which has one of the world’s longest-running college assignment mechanisms based on the deferred-acceptance (DA) algorithm.2 We take advantage of a recent policy change that increased the number of on-platform institutions from 25 to 33, raising the number of available slots by approximately 40%. We first present an analysis of the policy, which shows that when these options are included on the centralized platform, students start college sooner, are less likely to drop out, and are more likely to graduate within 7 years. Importantly, these effects are larger for students from lower-socioeconomic-status (SES) backgrounds, suggesting that the design of platforms can have effects on both efficiency and equity.

...

"We find that when students are allowed to express their preferences for a larger variety of options on the platform, welfare increases substantially, as does the share of students graduating on time.

...

"Intuitively, when a desirable program is not on the platform, it can cause some students who would have placed in that program to instead receive a placement in a different program available on the platform. These students may then decline that placement in favor of the off-platform program, creating vacancies that in turn lead to increased reliance on wait lists, which may be subject to frictions. Moreover, the absence of a particular program may distort the placements of other students, even if the students whose placements are affected would never enroll in that program. These students may also be less satisfied and more likely to decline their placement.

"Taken together, our results show empirically that the existence of off-platform options affects the equity and efficiency of centralized assignment systems. "

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Earlier (with some links to still earlier papers):

Monday, May 9, 2022

School choice with outside options , by Akbarpour, Kapor, Neilson, van Dijk, and Zimmerman in J.Pub.E.

Recent kidney transplant papers

 Here are two new papers on kidney exchange that caught my eye, and one on incentivizing deceased donation by prioritizing registered donors on the deceased donor waiting list.

This one concerns organizing international kidney exchanges between countries while making sure that each one gets their fair share. (All exchanges are between 2 pairs.)

Benedek, Márton, Péter Biró, Daniel Paulusma, and Xin Ye. "Computing balanced solutions for large international kidney exchange schemes." Autonomous Agents and Multi-Agent Systems 38, no. 1 (2024): 1-41.

Abstract: To overcome incompatibility issues, kidney patients may swap their donors. In international kidney exchange programmes (IKEPs), countries merge their national patient–donor pools. We consider a recently introduced credit system. In each round, countries are given an initial “fair” allocation of the total number of kidney transplants. This allocation is adjusted by a credit function yielding a target allocation. The goal is to find a solution that approaches the target allocation as closely as possible, to ensure long-term stability of the international pool. As solutions, we use maximum matchings that lexicographically minimize the country deviations from the target allocation. We perform, for the first time, a computational study for a large number of countries. For the initial allocations we use two easy-to-compute solution concepts, the benefit value and the contribution value, and four classical but hard-to-compute concepts, the Shapley value, nucleolus, Banzhaf value and tau value. By using state-of-the-art software we show that the latter four concepts are now within reach for IKEPs of up to fifteen countries. Our experiments show that using lexicographically minimal maximum matchings instead of ones that only minimize the largest deviation from the target allocation (as previously done) may make an IKEP up to 54% more balanced.

"We consider IKEPs in the setting of European KEPs which are scheduled in rounds, typically once in every three months.

...

"We first note that the search for an optimal exchange scheme can be done in polynomial time for 2-way exchanges (matchings) but becomes NP-hard as soon as 3-way exchanges are permitted."

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Here's a paper that reports simulations on Using deceased donor kidneys to start living donor kidney exchange chains

Verma, Utkarsh, Nayaran Rangaraj, Viswanath Billa, and Deepa Usulumarty. "Long term simulation analysis of deceased donor initiated chains in kidney exchange programs." Health Systems (2023): 1-12.

ABSTRACT: Kidney exchange programs (KEPs) aim to find compatible kidneys for recipients with incompatible donors. Patients without a living donor depend upon deceased donor (DD) donations to get a kidney transplant. In India, a DD donates kidneys directly to a DD wait-list. The idea of initiating an exchange chain starting from a DD kidney is proposed in a few articles (and executed in Italy in 2018), but no mathematical formulation has been given for this merger. We have introduced an integer programming formulation that creates DD-initiated chains, considering both paired exchange registry and DD allocations simultaneously and addressing the overlap issue between the exchange registry and DD wait-list as recipients can register for both registries independently. A long-term simulation study is done to analyse the gain of these DD-initiated chains over time. It suggests that even with small numbers of DDs, these chains can significantly increase potential transplants.

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And here's the paper on incentivizing registration to be a deceased donor.

Li, Mengling, and Yohanes E. Riyanto. "Incentivizing Organ Donation Under Different Priority Rules: The Role of Information." Management Science (2024).

Abstract: This paper examines the incentive to register for deceased organ donation under alternative organ allocation priority rules, which may prioritize registered donors and/or patients with higher valuations for organ transplantation. Specifically, the donor priority rule grants higher priority on the organ waiting list to those who have previously registered as donors. The dual-incentive priority rules allocate organs based on donor status, followed by individual valuations within the same donor status, or vice versa. Both theoretical and experimental results suggest that the efficacy of the donor priority rule and the dual-incentive priority rules critically depends on the information environment. When organ transplantation valuations are unobservable prior to making donation decisions, the hybrid dual-incentive rules generate higher donation rates. In contrast, if valuations are observable, the dual-incentive priority rules create unbalanced incentives between high- and low-value agents, potentially undermining the efficacy of the hybrid dual-incentive rules in increasing overall donation rates.

The ethics of field experiments in Economics, in the Financial Times

 The Financial Times has a column about the recent twitter (X) discussion concerning our paper Social Media and Job Market Success: A Field Experiment on Twitter, by Jingyi Qiu, Yan Chen, Alain Cohn, and Alvin E. Roth.

That twitter-up concerned whether it is ethical to do field experiments in economics, in which some argued that the benefits that might accrue to treated market participants may disadvantage untreated market participants, including those not involved in the experiment and from whom consent was not obtained. (The FT column has a paragraph in which Douglas MacKay*, a bio-ethicist from UNC considers ethical issues that might arise if the market "is a zero sum competition.") 

Here's the FT article, and the snippet that covers our paper.

When is it OK for economists to experiment on people? A recent study has raised ethical questions about research.  by Soumaya Keynes, Financial Times.

"While most economic debates are about as spicy as boiled potatoes, others generate a bit more heat. A recent stir fell into the second category, in response to a new study of junior academics angling for jobs in economics. 

...

"Alvin Roth, one of the authors of that experiment, says: “I can’t imagine economists thinking of a market as zero sum.” Perhaps a social media post could alert someone to a candidate so impressive that they persuade their university to make an extra position available. He points out that plenty of people share papers on social media, adding: “It seems to me that things that aren’t unethical to do shouldn’t be unethical to study to find out their effect.”

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Here's my earlier post, of the paper, with some thoughts on the ethics of experimenting.

Thursday, May 23, 2024

Social Media and Job Market Success: A Field Experiment on Twitter, by Qiu, Chen, Cohn, and Roth

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*And here is an interesting looking bibliography, including some papers by economists.

Ethics of Field Experiments: A Bibliography

Prepared and Managed by Emma Cohn and Douglas MacKay