Partial strategyproofness: Relaxing strategyproofness for the random assignment problem by Mennle and Seuken in JET

 Most market mechanisms that we encounter in practice aren't strategy proof, and many markets don't admit any strategyproof mechanisms, so we need to have a language to talk about how strategyproof a mechanism is or isn't.  There are a number of approaches to that, and here's a new one.

Partial strategyproofness: Relaxing strategyproofness for the random assignment problem

Timo Mennle  and Sven Seuken, Journal of Economic Theory, Volume 191, January 2021

Abstract: We present partial strategyproofness, a new, relaxed notion of strategyproofness for studying the incentive properties of non-strategyproof assignment mechanisms. Informally, a mechanism is partially strategyproof if it makes truthful reporting a dominant strategy for those agents whose preference intensities differ sufficiently between any two objects. We demonstrate that partial strategyproofness is axiomatically motivated and yields a parametric measure for “how strategyproof” an assignment mechanism is. We apply this new concept to derive novel insights about the incentive properties of the probabilistic serial mechanism and different variants of the Boston mechanism.

Prices and Decentralization Without Convexity: Milgrom's Arrow Lecture at Columbia (video)

 Columbia University Press posts a "video of Paul Milgrom's 2014 Kenneth J. Arrow Lecture that inspired Discovering Prices: Auction Design in Markets with Complex Constraints. Paul Milgrom discusses how prices can guide decentralized resource allocations in environments with non-convexities. His work on auctions led the Royal Swedish Academy of Sciences to award him and Robert Wilson the Nobel Memorial Prize in Economic Sciences for improvement to auction theory and invention of new auction formats."

Prices and Decentralization Without Convexity

****************

Related post:

Saturday, May 20, 2017

Discovering Prices, by Paul Milgrom

History and pre-history of kidney transplantation

 From the Hektoen International Journal (starting with an Egyptian papyrus from 1550 BCE):

A brief history of kidney transplantation by Laura Carreras-Planella, Marcella Franquesa, Ricardo Lauzurica, Francesc E. Borràs.  Barcelona, Spain

"The history of kidney transplantation as we know it today began in the 1950s, but other key attempts were made earlier in the twentieth century. The first successful organ transplant was performed by Emerich Ullmann from the Vienna Medical School in 1902 when he auto-transplanted a kidney in a dog from its normal location to the vessels of the neck, where it produced some urine.44,45 In the same year, dog-to-dog and dog-to-goat kidney transplants were performed by Ullmann and Alfred von Decastello, ... In 1906 Mathieu Jaboulay, with Carrel as assistant surgeon (both of them Nobel laureates), performed the first kidney transplantations from goats and pigs to the arms and thighs of humans. Each kidney worked for one hour only ... The first transplantation from a human cadaver was attempted in the USSR by Yurii Voronoy in 1939, although the organ was rejected because of blood group incompatibility and the patient died after two days.

...

"Investigations resumed after World War II with other attempts at human kidney transplantation, especially by two groups in Europe and the United States. In 1946 a human kidney allograft was transplanted to blood vessels in the arm under local anesthesia by a team in Boston.50 The graft only functioned for a short time, but it was long enough to help the patient recover from acute renal failure. This achievement attracted major interest, as did the first transplantation from a live donor performed by Jean Hamburger (who defined the term “nephrology”) in Paris from a mother to her sixteen-year-old son. The transplanted kidney functioned for twenty-two days.51 In 1950, Lawler in Chicago was the first to attempt intra-abdominal kidney transplantation.

"In 1954 at Peter Bent Brigham Hospital (later Brigham and Women’s Hospital) in Boston, Joseph Murray performed the first truly successful living donor kidney transplantation. He received the Nobel prize for this achievement in 1990. The transplant was performed from one monozygotic twin to the other, so there was no histo-incompatibility. This was the first time that a transplanted patient, who had been dying from renal failure, survived for years after the transplant.52 The procedure was met with growing success—one kidney recipient even had a successful pregnancy and delivery—and expanded to other hospitals. 53 The first kidney transplantation in Spain was performed in 1965 at the Hospital Clínic de Barcelona by Antoni Caralps, Pedro Pons, Gil-Vernet, and Magriñá, followed by eight additional transplantations at the same hospital that year.

"However, even though transplantation surgical techniques had greatly improved, good immunosuppressive regimens were still lacking. The use of the newly available azathioprine, prednisolone, or total body irradiation helped during the initial crucial rejection period between identical twins or siblings.54 In the mid-1960s, great improvements were made in the pre-treatment of patients with hemodialysis to enhance health before surgery; organ transportation between hospitals; identification of HLA antigens, discovered by Jean Dausset; development of tissue-typing and lymphocytotoxicity testing; and an increase in kidney transplants, which provided valuable data for improvement.55–57 Methodologies and management were consolidated in the 1970s, and saw the beginning of transplantations from cadaveric donors.

"But the most remarkable breakthrough of this period was the introduction of the calcineurin inhibitors cyclosporine A and tacrolimus. Cyclosporine A was first isolated in 1971 from a soil fungus (Hypocladium inflatum gams) in Norway and studied by Jean-Francois Borel and Hartmann F. Stähelin at Sandoz (now Novartis).58,59 The importance of this drug was reflected in the speed at which it was approved and released to the market in 1983. This small cyclic polypeptide made it possible to reduce the percentage of rejection in the first year after transplantation from 80% to 10%.60 Tacrolimus, somewhat better than cyclosporine A in reducing acute rejection and improving graft survival,61 was isolated from Streptomyces tsukubaensis in the soil of Tsukuba, Japan in 1987. The name tacrolimus derives from “Tsukuba macrolide immunosuppressant,” although it was initially called FK506 because of its target FK506 binding protein (FKBP).62,63,57 Mycophenolic acid, which was first isolated in 1893 from Penicillium glaucum in spoiled corn, was found to possess antibiotic activity but carried many adverse effects.64 A century later, its ester derivate mycophenolate mofetil was synthesized as a safer drug with immunosuppressant action.65,66 Rapamycin, also known as sirolimus and a current first-line immunosuppressant, was first found to be an antifungal metabolite of Streptomyces hygroscopicus. Discovered in Rapa Nui (formerly named Easter Island) in 1964, the name rapamycin comes from the site of its discovery.67–69 It is also abbreviated as mTOR because tor in German means door, and this protein serves as a gateway to cell growth and proliferation.70 Other analogs such as everolimus were synthesized later and are also routinely used in kidney transplantation.71 Although many immunosuppressive drugs are now in use, cyclosporine A and tacrolimus are still key in preventing organ rejection, even fifty years after their discovery."

Vouchers for organ donation, by Kim, Li, and Xu in JET

There are now a number of ways in which an organ donation (or registration as an organ donor) can turn into a future priority for receiving an organ.  Here's a paper from the January JET that looks at an overlapping generation model in which priority vouchers can be inherited by family members. The paper considers how, while this increases the incentive for the patriarch (or matriarch) of a family to register as a deceased donor, inheriting the voucher might reduce the incentive for descendants to donate, since they already have some priority on the deceased donor waiting list.  The paper models how this can be avoided by giving inherited vouchers increased priority when the current recipient registers.

Organ donation with vouchers by Jaehong Kim, Mengling Li, and Menghan Xu,  Journal of Economic Theory, Volume 191, January 2021, https://doi.org/10.1016/j.jet.2020.105159 

Abstract: The ever-increasing shortage of organs for transplantation has motivated many innovative policies to promote the supply of organs. This paper proposes and analyzes a general class of deceased organ allocation policies that assign priority on organ waiting lists to voucher holders to promote deceased donor registration. Priority vouchers can be obtained by self-registering for donation or through family inheritance. In an overlapping generations framework, we find that extending the donor priority benefits to future generations can improve the aggregate donation rate and social welfare. In particular, giving higher priority to voucher inheritors who register for donation is always beneficial regardless of the levels of population growth and care for future generations. By contrast, the efficacy of granting priority to nondonors with inherited vouchers depends on these two sociodemographic factors because of potential free-riding incentives.

 ***********

Related post:

Monday, September 26, 2016

The effects of Israel's new organ transplantation law on family consent for deceased donation

von Neumann Award to Matt Gentzkow

 Matt Gentzkow is the recipient of the 2021 John von Neumann Award.

"We are excited to announce that the Assembly of the College elected Professor Matthew Gentzkow as the recipient of the 2021 John von Neumann Award. We are grateful that the Professor accepted our invitation to Budapest to receive the prize and give the John von Neumann Lecture once the pandemic situation permits.

"Matthew Gentzkow is a Professor of Economics at Stanford University where he studies applied microeconomics with a focus on media industries. Members of the College chose him for the 2021 John von Neumann award because of the substantive findings of his research on the political economy of the media market as well as his innovative use of new methods and data – especially the quantitative analysis of text. He received the 2014 John Bates Clark Medal, given by the American Economic Association to the American economist under the age of forty who has made the most significant contribution to economic thought and knowledge. He is a fellow of the American Academy of Arts and Sciences and the Econometric Society, a senior fellow at the Stanford Institute for Economic Policy Research, and a former co-editor of American Economic Journal: Applied Economics

"The John von Neumann Award, named after John von Neumann is given annually by the Rajk László College for Advanced Studies (Budapest, Hungary), to an outstanding scholar in the exact social sciences, whose works have had substantial influence over a long period of time on the studies and intellectual activity of the students of the college. The award was established in 1994 and is given annually. In 2013, separately from the annual prize, Kenneth J. Arrow was given the Honorary John von Neumann Award."

New Israeli anti-prostitution law: the johns are now criminals

With the new year, the Israeli law that makes it a crime to hire prostitutes goes into effect. 

Haaretz has the story:

 Israel's Anti-prostitution Law Could Start a Revolution, but Only if Authorities Aim Higher--Enforcement, rehabilitation, prevention and education are needed for Israel to truly claim its place among the ranks of progressive countries fighting to end prostitution and human trafficking  by Vered Lee

"In honor of the new calendar year, Israel is joining the list of progressive countries fighting to end prostitution – a list that includes Sweden, Canada, France and Ireland. As of Thursday, it began enforcing a law banning the use of prostitutes.

...

"Moreover, the law doesn’t criminalize people trapped in prostitution, thereby sending the message that they are victims in the eyes of the law. This breaks the old mold and could therefore, for the first time, give them power against the clients and pimps in the prostitution industry. It is also a clear statement that prostitution isn’t a choice, but a lack of choice.

"The law forbidding the use of prostitutes was sponsored by the government. It’s a temporary law that will remain in effect for five years, during which its impact will be studied. One of the law’s important provisions is that it requires the state to offer rehabilitation to people trapped in the prostitution industry.

...

"Now that a legal and public spotlight is being shined on prostitutes’ clients, it must be said clearly that the time has come not only to punish them, but also to rehabilitate them. Just recently, nauseating Israeli sex tourism to the United Arab Emirates has hit the headlines. This isn’t a new problem; Israeli sex tourists are also infamous in Thailand.

"But on the day the law to fight the local prostitution industry came into force, Israel also committed to fight the consumption of paid sex by its citizens overseas and to try to prevent the problem from migrating to other countries."

Randomized control trials plus preferences: a market design for experiments by Yusuke Narita in PNAS

 Random assignment of patients to experimental treatments is intended to allow statisticians to cleanly measure the effect of the treatments. But if there is evidence that some patients might profit more from some treatment than others, fully random assignment may not maximize health outcomes. And if patients have preferences (e.g. for the risk of receiving a problematic kidney for transplant versus the risk of waiting for a better one), then fully random assignment may not maximize welfare.  Yusuke Narita thinks about how to design RCTs that elicit patient preferences and take account of prior's about outcomes, while still allowing the necessary statistical tests to determine treatment effects.

Incorporating ethics and welfare into randomized experiments  by Yusuke Narita

PNAS January 5, 2021 118 (1) e2008740118; https://doi.org/10.1073/pnas.2008740118

Edited by Parag Pathak, Massachusetts Institute of Technology, Cambridge, MA, and accepted by Editorial Board Member Paul R. Milgrom September 30, 2020 

"Abstract: Randomized controlled trials (RCTs) enroll hundreds of millions of subjects and involve many human lives. To improve subjects’ welfare, I propose a design of RCTs that I call Experiment-as-Market (EXAM). EXAM produces a welfare-maximizing allocation of treatment-assignment probabilities, is almost incentive-compatible for preference elicitation, and unbiasedly estimates any causal effect estimable with standard RCTs. I quantify these properties by applying EXAM to a water-cleaning experiment in Kenya. In this empirical setting, compared to standard RCTs, EXAM improves subjects’ predicted well-being while reaching similar treatment-effect estimates with similar precision.

...

"RCTs involve large numbers of participants. Between 2007 and 2017, over 360 million patients and 22 million individuals participated in registered clinical trials and social RCTs, respectively. Moreover, these experiments often randomize high-stakes treatments. For instance, in a glioblastoma therapy trial (1), the 5-y death rate of glioblastoma patients was 97% in the control group, but only 88% in the treatment group. In expectation, therefore, the lives of up to 9% of the study’s 573 participants depended on who received treatments. Social RCTs also often randomize critical treatments such as basic income, high-wage job offers, and HIV testing.

"RCTs, thus, influence the fate of many people around the world, raising a widely recognized ethical concern with the randomness of RCT treatment assignment: “How can a physician committed to doing what he thinks is best for each patient tell a woman with breast cancer that he is choosing her treatment by something like a coin toss? How can he give up the option to make changes in treatment according to the patient’s responses?”

...

"I propose an experimental design that I call Experiment-as-Market (EXAM). I choose this name because EXAM is an experiment based on an imaginary centralized market and its competitive equilibrium (12, 13). EXAM first endows each subject with a common artificial budget and lets her use the budget to purchase the most preferred (highest WTP) bundle of treatment-assignment probabilities given their prices. The prices are personalized so that each treatment is cheaper for subjects with better predicted effects of the treatment. EXAM computes its treatment-assignment probabilities as what subjects demand at market-clearing prices, where subjects’ aggregate demand for each treatment is balanced with its supply or capacity (assumed to be exogenously given). EXAM, finally, requires every subject to be assigned to every treatment with a positive probability.

"This virtual-market construction gives EXAM nice welfare and incentive properties. EXAM is Pareto optimal, in that no other design makes every subject better off in terms of expected predicted effects of and WTP for the assigned treatment. EXAM also allows the experimenter to elicit WTP in an asymptotically incentive-compatible way. That is, when the experimenter asks subjects to self-report their WTP for each treatment to be used by EXAM, every subject’s optimal choice is to report her true WTP, at least for large experiments.

"Importantly, EXAM also allows the experimenter to estimate the same treatment effects as standard RCTs do. Intuitively, this is because EXAM is an experiment stratified on observable predicted effects and WTP, in which the experimenter observes each subject’s assignment probabilities (propensity scores). As a result, EXAM’s treatment assignment is random (independent from anything else), conditional on the observables. The conditionally independent treatment assignment allows the experimenter to unbiasedly estimate the average treatment effects (ATEs) conditional on observables. By integrating such conditional effects, EXAM can unbiasedly estimate the (unconditional) ATE and other effects, as is the case with any stratified experiment (14)."

**********

somewhat related post:

Sunday, July 12, 2020

Incorporating patient preferences into transplant decisions can improve welfare--Genie, Nicolo and Pasini in J Health Economics

The Short-Side Advantage in Random Matching Markets by Linda Cai and Clayton Thomas (guest post by Itai Ashlagi)

 Itai Ashlagi writes: 

Linda Cai and Clayton Thomas, both graduate students, have a very short, elegant and straightforward proof for why the short side has a large advantage in two-sided matching markets with uniformly random generated preferences (in a large market with n men and n+1 women, in any stable matching men get on average their logn rank and women get on average their n/logn rank).   Here is the paper.

So let’s just describe the proof.

Quick background:

In a balanced market with n people on each side, the men-proposing deferred acceptance (MPDA) terminates the moment all women received at least one proposal. It is quite straightforward to show that this happens after O(nlogn) proposals by men. Why?  The number of proposals dominates (but very similar) to the number of steps in the famous “coupon collector” problem: there are n different coupons which are drawn with replacement until all coupons are drawn: the number of draws is the sum of expectations of geometric random variables, which sums to n times the n-th harmonic, or O(nlogn).   So each man makes on average O(logn) proposals. Since women receive on average O(logn) proposals their average rank for their stable partner is least n/logn.

A lemma by Immorlica and Mahdian, in another beautiful and important paper: a woman w* has a stable partner who she ranks better than k if and only if w* remains matched in the MPDA when she truncates her list after rank k. well, matching theory….

Let’s go to the market with n men and n+1 women:

By the lemma, w*’s rank in a woman-optimal stable matching is the minimum rank k she can truncate her list at while still being matched under MPDA.   Now suppose w* decides to reject all proposals she receives.  Run MPDA until it terminates - when all women other than w* receive a match. The total number of proposals from men is again like the coupon collector, O(nlogn).  And so w* received an average of O(logn) proposals. So she cannot expect to have a stable partner she ranks better than n/logn (and in expectation will remain unmatched if she truncates below that).

Vaccine supply chain woes

Supply chains are boring, until things are in short supply. And there are many steps in a supply chain that can cause supplies to be short. Below are some news stories on how the U.S. is having trouble delivering vaccines, with the limiting factors not yet being shortage of the vaccines themselves.

I notice a few things about these stories. 

• It seems to be widely recognized that it is worth spending billions (or at least hundreds of millions) to save trillions (i.e. to speed up vaccinations to hasten the reopening of the economy).
• It seems also to be widely recognized that it would be regarded as repugnant to allocate initial inoculations by charging high prices for them while they are scarce: instead we are trying to establish priority orders for recipients: e.g. first health care workers and the elderly in nursing homes, then the independent elderly and the ill, etc,
• Keeping strictly to priorities may partly be what is slowing down vaccinations: when not enough high priority people show up, the vaccines go back in the freezer to wait for the next day (at least I hope they go back in the freezer, and are not spoiled and unusable by the next day).  It might be better to try to find people ready to be vaccinated, when it's hard to find enough high priority people quickly.
• A lack of confidence that more vaccine doses will be reliably arriving on schedule is causing some stockpiling, which is the enemy of fast distribution.
• Holiday schedules make it hard to get lots of people vaccinated fast; maybe we'll do better this coming week.

Here's a story from the Financial Times:

Trump administration admits missing Covid vaccination goals--Officials say US states have used only a fifth of the doses they were given  by Kiran Stacey 

"Officials had aimed to distribute enough doses to vaccinate 20m people by the end of the year, but recently admitted they were not likely to hit that target until early January after underestimating how long it would take to perform quality control checks on manufactured doses.

"Figures released by the federal government, however, show a bigger hurdle is getting the vaccines to people once they have been manufactured and sent out. The US Centers for Disease Control and Prevention said on Wednesday just under 2.6m people in the country had been vaccinated, even though 12.4m doses had been distributed.

...

"Nancy Messonnier, the director of the National Center for Immunisation and Respiratory Diseases, blamed a range of factors. She said part of the problem was that pharmacies that were largely responsible for vaccinating people in care homes had been waiting to schedule appointments until they could be sure they had enough doses to perform booster shots."

************

From the NY Times:

Here’s Why Distribution of the Vaccine Is Taking Longer Than Expected--Health officials and hospitals are struggling with a lack of resources. Holiday staffing and saving doses for nursing homes are also contributing to delays.  By Rebecca Robbins, Frances Robles and Tim Arango

"In Florida, less than one-quarter of delivered coronavirus vaccines have been used, even as older people sat in lawn chairs all night waiting for their shots. In Puerto Rico, last week’s vaccine shipments did not arrive until the workers who would have administered them had left for the Christmas holiday. In California, doctors are worried about whether there will be enough hospital staff members to both administer vaccines and tend to the swelling number of Covid-19 patients.

"These sorts of logistical problems in clinics across the country have put the campaign to vaccinate the United States against Covid-19 far behind schedule in its third week, raising fears about how quickly the country will be able to tame the epidemic.

...

"Complicating matters, the county health department gets just a few days of notice each week of the timing of its vaccine shipments. When the latest batch arrived, Dr. Gayles’s team scrambled to contact people eligible for the vaccine and to set up clinics to give out the doses as fast as possible.

...

"In Florida, some hospital workers offered the vaccine declined it, and those doses are now designated for  other vulnerable groups like health care workers in the community and the elderly, but that rollout has not quite begun

...

"It may be more difficult, public health officials say, to vaccinate the next wave of people, which will most likely include many more older Americans as well as younger people with health problems and frontline workers. Among the fresh challenges: How will these people be scheduled for their vaccination appointments? How will they provide documentation that they have a medical condition or a job that makes them eligible to get vaccinated? And how will pharmacies ensure that people show up, and that they can do so safely?"

A hopeful picture for 2021 (when vaccines will replace masks...)

 

Original at https://pbs.twimg.com/media/EqayYuaXEAE7YCu.jpg

HT: Mike Rees

Hypertension: the surgeon general calls for a New Year's resolution

 The U.S. Public Health Service has issued the following call to action on high blood pressure, which affects many Americans, differentially across race, ethnicity and socioeconomic status:

The Surgeon General’s Call to Action to Control Hypertension

"Hypertension, or high blood pressure, affects nearly one in two U.S. adults and is a major preventable risk factor for heart disease and stroke.1  Despite the common nature of this condition and a large amount of national attention,2,3  only about 24% (26 million) have their blood pressure controlled to ≤130/80 mmHg.1  Regardless of the threshold used to measure control, national rates have stagnated and disparities persist.3,4 The Surgeon General’s Call to Action to Control Hypertension seeks to avert the negative health effects of hypertension across the U.S. by identifying interventions that can be implemented, adapted, and expanded across diverse settings.

The Call to Action is divided into three sections. Section 1 summarizes the current state of  hypertension control, including the economic costs and disparities between different population groups. It notes that progress in hypertension control has been demonstrated in communities and health care systems across the country.5,6,7  In many areas, we know what works, but we need to replicate and expand these efforts and continue to explore new interventions to achieve control across all population groups.

Section 2 presents three overall goals to support improvements in hypertension control:

Goal 1. Make hypertension control a national priority.

Goal 2. Ensure that the places where people live, learn, work, and play support hypertension control.

Goal 3. Optimize patient care for hypertension control.

The year in passings

This year I noted the following deaths with particular significance to readers of this blog:

Monday, December 21, 2020 

Edward (Eddie) Lazear (1948-2020)

Saturday, November 7, 2020

Bernard Cohen (1934-2020), who convinced the Supreme Court that bans on inter-racial marriage were unconstitutional

Thursday, October 1, 2020

Becky Morton, RIP

Wednesday, July 29, 2020

Emmanuel Farhi 1978-2020

Saturday, July 18, 2020

Bill Sandholm (1970-2020)

Sunday, May 31, 2020

What values do we bequeath to our grandchildren? Alberto Alesina et al. on the generations following the Cultural Revolution in China

Sunday, May 24, 2020

Olly Williamson (1932-2020)

Tuesday, April 14, 2020

John Horton Conway (1937-2020)

A hard (theoretical) look at school choice, in the AER by Chris Avery and Parag Pathak

 What are some of the difficulties that might hamper school choice from achieving educational equality (or at least substantially reducing inequality)?  Here's a model by Chris Avery and Parag Pathak.  The theoretical intuitions of top experts in college and school assignments are the sort of thing that can keep you awake at night.  In a sentence, if school choice narrows the quality gap between the best and worst municipal schools, it may also narrow the gap in housing prices, and higher housing prices at the low end may drive poorer families to move to other school districts, just as lower quality at the high end drives richer families to suburbs with excellent schools. ("White flight" has been the subject of many papers, so the issue being raised here is that an improvement at the low end of school quality may also raise prices of less expensive housing and drive out poorer residents.)

The Distributional Consequences of Public School Choice  by Christopher Avery and Parag A. Pathak AMERICAN ECONOMIC REVIEW, VOL. 111, NO. 1, JANUARY 2021, (pp. 129-52)

"Abstract: School choice systems aspire to delink residential location and school assignments by allowing children to apply to schools outside of their neighborhood. However, choice programs also affect incentives to live in certain neighborhoods, and this feedback may undermine the goals of choice. We investigate this possibility by developing a model of public school and residential choice. School choice narrows the range between the highest and lowest quality schools compared to neighborhood assignment rules, and these changes in school quality are capitalized into equilibrium housing prices. This compressed distribution generates an ends-against-the-middle trade-off with school choice compared to neighborhood assignment. Paradoxically, even when choice results in improvement in the lowest-performing schools, the lowest type residents need not benefit."

"Our analysis contributes to a recent literature on school choice mechanisms, which has focused on the best way to assign pupils to schools given their residential location in a centralized assignment scheme. In particular, research has examined the best way to fine-tune socioeconomic or income-based criteria in choice systems. Cities have now experimented with complex school choice tie-breakers in an effort to achieve a stable balance (Kahlenberg 2003). 17 By incorporating feedback between residential and school choices, our model suggests that analysis of school assignment that does not account for possible residential resorting may lead to an incomplete understanding about the distributional consequences of school choice.

"A common rationale for school choice is to improve the quality of school options for disadvantaged students. But, our analysis shows that feedback from residential choice can undercut this approach, for if a school choice plan succeeds in narrowing the range between the lowest and highest quality schools, that change should compress the distribution of house prices in that town, thereby providing incentives for the lowest and highest types to exit from the town’s public schools. This intuition extends to the idealized case of a symmetric model of many towns and partisans, where each town adopts school choice and all schools within a given town have the same quality. Although there is an equilibrium in this idealized model where schools in all towns have the same quality, this equilibrium would likely be unstable, and instead we would expect to observe an equilibrium with differentiation of school qualities and housing prices across towns. That is, the within-town diversity observed in equilibrium under neighborhood assignment could be replicated in cross-town diversity under school choice.

A broader implication of our model is that systemic changes beyond the details of the school assignment system may be necessary to reduce inequalities in educational opportunities."

College admissions in Australia, by Guillen, Kesten, Kiefer, and Melatos

 Here's a working paper from the University of Sydney that looks at the New South Wales college admissions clearinghouse in which students receive (accurate but unclear) advice from the clearinghouse operator, together with clear but incorrect advice from individual universities.  In an experiment, they look at the effects of these different kinds of advice when presented separately and together.

A Field Evaluation of a Matching Mechanism: University Applicant Behaviour in Australia by Pablo Guillen Onur Kesten, Alexander Kiefer, and Mark Melatos  December 2020

"Abstract: The majority of undergraduate university applications in the state of New South Wales –Australia’s largest state – are processed by a clearinghouse, the Universities Admissions Centre (UAC). Applicants submit an ordered list of degree preferences to UAC which applies a matching algorithm to allocate university places to eligible applicants. The algorithm incorporates the possibility of a type of “early action” through which applicants receive guaranteed enrolments. Applicants receive advice on how to construct their degree preference list from multiple sources (including individual universities). This advice is often confusing, inconsistent with official UAC advice or simply misleading. To evaluate the policy implications of this design choice, we run a large sample (832 observations) experiment with experienced participants in a choice environment that mimics the UAC application process and in which truth telling is a dominant strategy. We vary the advice received across treatments: no advice, UAC advice only, (inaccurate) university advice only, and both UAC and university advice together. Overall, 75.5% of participants fail to use the dominant strategy. High rates of applicant manipulation persist even when applicants are provided with accurate UAC advice. We find that students who attend non-selective government schools are more prone to use strictly dominated strategies than those who attend academically selective government schools and private schools."

The matching algorithm, in which applicants are allowed to list only six choices, is described as follows:

"The algorithm used by UAC sequentially checks each applicant’s eligibility for a degree starting with her first choice. It is therefore reminiscent of the Boston mechanism widely used for school choice in the U.S. (Abdulkadiroglu et al, 2005; Abdulkadiroglu et al, 2006) and college admissions in China (Chen and Kesten, 2017) among other places. However, the absence of formal capacity constraints (on university enrolments) makes this Australian context a unique instance in which the outcome of the algorithm also coincides with that of the celebrated Deferred Acceptance (DA) algorithm of Gale and Shapley (1962). Due to this equivalence, the UAC algorithm does not inherit the strategic vulnerability of the Boston algorithm. Consequently, students are still able to construct their preferred degree list in a manner that is consistent with their true preferences.4

"While the UAC admissions system appears similar to a typical college admissions problem (see, e.g., Roth and Sotomayor, 1991 and Balinski and Sönmez, 1998), universities in NSW can influence student applications through an additional channel. To limit the uncertainty faced by applicants,5 many universities often grant applicants “guaranteed entry” options.6 These schemes represent a university’s commitment to an individualised entry requirement for a particular degree, subject to the candidate’s achievement of a certain score. This innovative feature of the UAC system can be viewed as the centralized or algorithmic embodiment of “early decision” schemes used by over two-thirds of top colleges in the US (see, e.g., Avery, Fairbanks, and Zeckhauser, 2004) that admit students through a decentralized system.7 Indeed, we are not aware of any other centralized college admissions system that has this type of feature. Under the current UAC algorithm, if an applicant includes a guaranteed entry degree in her preference list, this implies that she will not be considered for any degree that she has listed lower on her list provided that she attains the pre-announced entry score."

They conclude in part that

"accurate, albeit somewhat complicated, advice may fail to mitigate the impact of inaccurate (but straightforward) advice."

The cost of a horse's smile (and the supply chain of chess sets)

 Among the pandemic shortages (along with toilet paper) are chess sets, whose sales have soared in response to the Netflix series "The Queen's Gambit." Chess sets, even wooden ones (as opposed to sets made of exotic materials), can be expensive. The NY Times explain why:

What Are You Paying For in a $300 Chess Set? Mostly the Knights.  The horses in higher-end wooden sets must be hand-carved, a long, specialized process to make sure all four are exactly the same.  by Sophia June

"If you bought a wooden chess set after watching “The Queen’s Gambit,” the price you paid was most likely dictated by just four pieces.

"The knights alone can account for as much as 50 percent of the cost of a nice wooden set. While the rest of the pieces can be machine-made, the knights are carved by hand to resemble the head of a horse, a tedious process to make sure all four are exactly the same.

"The knights in the set used in World Chess Championship matches ($310 for the pieces and $220 for the board) were inspired by a horse carving from the Parthenon in Athens, said Ilya Merenzon, the chief executive of World Chess, the company that licenses the rights to the matches. The process of creating the set when it was redesigned in 2013 required extensive back-and-forth communication with carvers in India to discuss minutiae like the horse’s smile.

"About 10 people specialize in carving knights for the World Chess sets, Mr. Merenzon said. It takes about two weeks to produce 100 sets, with a set of knights requiring about six hours to carve, he said.

...

"In the higher-end sets, “you can literally see the teeth carved into the horse’s mouth,” said Noelle Kendrick, the House of Staunton’s business development director. “They are extremely detailed. You can see the mane, the rivets of the mane, if it has a flowing mane.”

***********

***********

Here's a related article:

‘The Queen’s Gambit’ Sends Chess Set Sales Soaring by Marie Fazio,

and here's a blog post on Knights:

Tuesday, April 1, 2014

Knight Management, and the Knight Way

Global chocolate production and consumption

This map  of cocoa production and consumption from the Cocoa Barometer 2020 would make it easy to guess which way is North (were it not for Australia)...

 

Global markets in antiquity: olive oil and wine

Markets are ancient human artifacts, and a recent paper in the EJ suggests that markets of global scale, based on comparative advantage and international trade, are older than previously recognized.  Global (or at least international) agricultural markets are ancient, according to pollen data on crops and population in ancient Greece:

Landscape Change and Trade in Ancient Greece: Evidence from Pollen Data  by Adam Izdebski, Tymon Słoczyński, Anton Bonnier, Grzegorz Koloch, Katerina Kouli, The Economic Journal, Volume 130, Issue 632, November 2020, Pages 2596–2618, https://doi.org/10.1093/ej/ueaa026

"Abstract: In this article we use pollen data from six sites in southern Greece to study long-term vegetation change in this region from 1000 BCE to 600 CE. Based on insights from environmental history, we interpret our estimated trends in the regional presence of cereal, olive and vine pollen as proxies for structural changes in agricultural production. We present evidence that there was a market economy in ancient Greece and a major trade expansion several centuries before the Roman conquest. Our results are consistent with auxiliary data on settlement dynamics, shipwrecks and ancient oil and wine presses."

" We demonstrate that in a period of apparent population growth southern Greece decreased its relative production of cereals. We also observe a simultaneous increase in the relative importance of olives and vines. Since southern Greece had a comparative advantage in the production of olive oil and wine, we interpret this result as evidence of a trade expansion. The growing demand for wheat could only have been satisfied by massive grain imports, perhaps from the Black Sea region, which were offset by exports of olive oil and wine. These commodities were in high demand in Greek colonies and other neighbouring areas, which needed them for cultural reasons but were not always able to produce them locally."

A chain of 900 strangers...

 When I talk about chains on this blog, I'm almost always talking about kidney exchange.  But there are other kinds of gift giving chains. The Washington Post has this cheerful story:

A chain of 900 strangers bought one another’s meals at a Dairy Queen drive-through  By Cathy Free

"It started with an older gentleman who pulled up to the Dairy Queen Grill & Chill drive-through window in Brainerd, Minn., at the height of the lunch hour on a Thursday.

“I’d also like to pay for the car behind me,” cashier Darla Anderson said the customer told her on Dec. 3. “Whatever they’ve ordered, I’ll cover it.”

...

"two days and hundreds of cars later, she and the rest of the crew were still ringing up “pay it forward” orders as each person who came to the drive-through offered to pay for the car behind them.

“I’ve seen ‘pay it forward’ chains that went on for about 20 cars, but never anything like this,” said general manager Tina Jensen, 43.

"In the end, it spanned more than 900 cars over 2½ days.

"On the first day, Jensen watched as hour after hour customers paid for the ice cream and hamburgers of the strangers behind them. So she decided to write a quick post on the Dairy Queen Facebook page.

...

"People who saw the post wanted to join in, and a long line of cars was soon snaking along the drive-through lane.

...

"The first two evenings of the pay-it-forward chain, before Dairy Queen closed for the night, Jensen gave the last person at the drive-through the option to leave a few dollars to pay it forward for the first customer the next day.

...

"The chain was finally broken early in the evening Dec. 5, she said, when a customer said he didn’t have enough money to pay for the order behind him, which cost more than his. The restaurant was out of carry-over funds left by other customers."

Fast Covid vaccine development --science and funding

 Here's a news article from Nature:

The lightning-fast quest for COVID vaccines — and what it means for other diseases.

The speedy approach used to tackle SARS-CoV-2 could change the future of vaccine science. by Philip Ball

"The research that helped to develop vaccines against the new coronavirus didn’t start in January. For years, researchers had been paying attention to related coronaviruses, which cause SARS (severe acute respiratory syndrome) and MERS (Middle East respiratory syndrome), and some had been working on new kinds of vaccine — an effort that has now paid off spectacularly.

"Conventional vaccines contain viral proteins or disabled forms of the virus itself, which stimulate the body’s immune defences against infection by a live virus. But the first two COVID-19 vaccines for which efficacy was announced in large-scale (phase III) clinical trials used just a string of mRNA inside a lipid coat. The mRNA encodes a key protein of SARS-CoV-2; once the mRNA gets inside our cells, our bodies produce this protein. That acts as the antigen — the foreign molecule that triggers an immune response. The vaccines made by Pfizer and BioNTech and by the US pharmaceutical company Moderna both use mRNA that encodes the spike protein, which docks to human cell membranes and allows the coronavirus to invade the cell.

...

"The approach has matured just at the right time; five years ago, the RNA technology would not have been ready.

...

"The slowest part of vaccine development isn’t finding candidate treatments, but testing them. This often takes years (see ‘Vaccine innovation’), with companies running efficacy and safety tests on animals and then in humans. Human testing requires three phases that involve increasing numbers of people and proportionately escalating costs. The COVID-19 vaccines went through the same trials, but the billions poured into the process made it possible for companies to take financial risks by running some tests at the same time."

HT: Muthu Muthukrishnan

Celebrating Ramanujan's birthday (with some math quotes)

 Yesterday, 22 December, is celebrated every year as National Mathematics Day in India, in honor of the 1887 birthday of the great Indian mathematician Ramanujan.

Here are some quotes about math in honor of the day, in the Indian periodical RepublicWorld.com

Mathematics Day: Here are some of the most inspirational Happy Mathematics Day quotes on Ramanujan's birthday to honour this special occasion.  By Vageesha Taluja

Not included in that collection of quotes is this one, attributed in Wikipedia to Ramanujan himself: "An equation for me has no meaning unless it expresses a thought of God."

I was pleasantly surprised to see included something much more prosaic that I  was quoted as saying, in a 2010 profile in Forbes magazine called Un-Freakonomics, by Susan Adams: 

"I've always been interested in using mathematics to make the world work better." -Alvin E. Roth