research
Working papers and work in progress
Managing Congestion in Two-Sided Platforms: The Case of Online Rentals
Joint with Laura Doval, Alejandro Robinson-Cortés and Matt Shum
Thick two-sided matching platforms, such as the room-rental market, face the challenge of showing relevant objects to reduce search frictions. Many platforms use simple ranking algorithms to determine the search results that users are shown, often breaking ties with a random number. The main problem is that rough criteria to determine exposure is the same for all users. Using rich data on a room rental platform we show that such simple ranking algorithms create an inefficient source of congestion, inducing individuals to view, click, and request the same rooms. This greatly limits the number of matches created by the platform. We estimate preferences semiparametrically and simulate counterfactuals under different search algorithms. The counterfactual number of views, requests and matches that can be generated if rooms are shown differently is larger.
[Paper in PDF]
The design of university entrance exams and its implications for gender gaps
Joint with Andreu Arenas
Revise and Resubmit at Management Science
Abstract: We investigate the effect of increasing the weight of standardized high-stakes exams at the expense of high school grades for college admissions. Studying a policy change in Spain, we find a negative effect of the reform on female college admission scores, driven by students expected to be at the top. The effect on admission scores does not affect enrolment, but the percentage of female students in the most selective degrees declines, along with their career prospects. Using data on college performance of pre- reform cohorts, we find that female students most likely to lose from the reform tend to do better in college than male students expected to benefit from the reform. The results show that rewarding high-stakes performance in selection processes may come along with gender differences unrelated to the determinants of subsequent performance.
[Paper in PDF]
The Impact of Formative Assessment on Behavior-Based Sociomemotional Skills on Students' Outcomes
Joint with Giacomo de Giorgi and Laia Navarro AEA Registry AEARCTR-0010447
It is widely recognized that social and personal skills (i.e., perseverance, motivation, teamwork, etc.) are highly predictive of life achievements and long-term well-being, such as lower levels of school dropout, physical and mental health issues, and conflict. It is also well established that a comprehensive integration of these non-cognitive skills in the educational curriculum is essential to make lifetime progress.
The objective of this trial is to test the causal impact of training and mentoring teachers to integrate formative assessment of socioemotional skills in the classroom with the help of digital tools on students’ academic and non-cognitive outcomes. Formative assessment by the trained teachers involves the observation, recording, and provision of feedback on a specific set of behaviors, the so-called Pentabilities, that characterize socioemotional skills in active classroom environments. The teachers are given 5-6 months to implement the intervention. The trial involves 40 Catalan secondary schools that mainly serve at-risk populations.
Evidence of tutoring, mentoring and support programs for the improvement of reading and mathematics competences
Joint with Giacomo de Giorgi, Javier Garcia Brazales, Jenifer Ruiz-Valenzuela and Davide Viviano AEA Registry AEARCTR-0010448
The objective of this study is to provide evidence about the effectiveness of two interventions providing educational support, one for reading and one for mathematics, in low-socioeconomic schools located in Spain. The reading program consist of one-on-one mentoring sessions for grade 4 students aimed at fostering the pleasure for autonomous reading, The mathematics program consists of four-group tutorial sessions for grade 6 students. Within the classes of the grade for which the school is treated, only a subset of students will actually participate in our tutoring/mentoring programs.
Assigning half of the pool of participating schools into the reading program and the other half into the mathematics program, we will compare the outcomes of the students from the grade for which the school has been treated with the outcomes of the students in the same grade from schools that got assigned to the other program. Within a given treated class, students who did not actually participate in the mentoring/tutoring programs might still have their outcomes impacted through in-class spillovers.
Naturally, we will explore the impact of our intervention on reading and mathematics cognitive abilities. We will pay particular attention to how these programs affect the classroom depending on the position in the network of friends where the treated kids belong. We also explore other dimensions such as improvements in socio-emotional skills, classroom climate and behavior, and changes in social relations and friendships.
The impact of Mentoring on Tertiary Education Expectations
Joint with Annalisa Loviglio and Javier Garcia Brazales AEA Registry AEARCTR-0012319
Abstract: Access to tertiary education among students enrolled in schools located in socioeconomically-disadvantaged areas is still limited. This fact tends to perpetuate inequalities. In this project, we study the impact of providing one-to-one mentoring sessions to students starting their last year of high school by randomly allocating a subset of students from over 50 schools in Catalonia to voluntary mentors who are college students or graduates. We focus on the effects of our intervention on the expectations of these students about the likelihood of attending university or vocational education and of direct entry into the labor force and about the pecuniary and non-pecuniary returns of these three options.
The impact of professional and volunteer mentoring on university access and retention
Joint with Annalisa Loviglio AEA Registry AEARCTR-0010785
Abstract: The project aims to understand the impact of mentoring programs on high school students in Catalonia, Spain, with a focus on their performance and persistence in tertiary education. Additionally, it investigates the disparities in outcomes between being paired with a volunteer mentor versus an educational technician (ET). Employing randomized controlled trials at two levels – first at the school level and then within pairs of individuals – the project seeks to evaluate short and medium-term educational outcomes. These outcomes include persistence in tertiary education and career satisfaction. Volunteers, typically university students or graduates residing in Spain, offer firsthand experience, while ETs oversee pairs and provide mentorship. By assessing the effects of these interventions, the project aims to offer insights into effective strategies for improving educational equity and career outcomes. It considers varying approaches and resource allocations between volunteer and professional mentors.
The Labor Market Returns to Dual Vocational Education
joint with Samuel Bentolila, Marcel Jansen, and Francisco Vale
Publications
Tailoring Mentorship: Evidence on Diverse Needs and Application Patters for High School Students"
Joint with Javier Garcia-Brazales and Annalisa Loviglio
forthcoming in the 2024 AEA Papers and Proceedings
Catchment Areas, Stratification and Access to Better Schools
Joint with Antonio Miralles
International Economic Review, May 2023.
Abstract: Details about how choice is implemented and the features of the underlying market are key for the success of the matching procedure. Literature assumes that whenever choice is implemented, the allocation is going to be different than in the absence of choice. In a large market with school strati.cation and where priority is given to residents in the catchment area of the school, we show that both the Boston Mechanism and Deferred Acceptance, the most popular assignment mechanisms, have a limited capacity to provide access to better schools (ABS) and hence that the default school is likely to remain the assigned option. Top-Trading Cycles is an alternative that provides more access to better schools than DA.
[Paper in PDF]
What is at stake without high-stakes exams? Students' evaluation and admission to college at the time of COVID-19
Joint with Andreu Arenas and Annalisa Loviglio
Economics of Education Review, 83, August 2021.
Abstract: The outbreak of COVID-19 in 2020 inhibited face-to-face education and constrained exam taking. In many countries worldwide, high-stakes exams happening at the end of the school year determine college admissions. This paper investigates the impact of using historical data of school and high-stakes exams results to train a model to predict high-stakes exams given the available data in the Spring. The most transparent and accurate model turns out to be a linear regression model with high school GPA as the main predictor. Further analysis of the predictions reflect how high-stakes exams relate to GPA in high school for different subgroups in the population. Predicted scores slightly advantage females and low SES individuals, who perform relatively worse in high-stakes exams than in high school. Our preferred model accounts for about 50% of the out-of-sample variation in the high-stakes exam. On average, the student rank using predicted scores differs from the actual rank by almost 17 percentiles. This suggests that either high-stakes exams capture individual skills that are not measured by high school grades or that high-stakes exams are a noisy measure of the same skill.
School Choice Design, Risk Aversion and Cardinal Segregation
Joint with Francisco Martinez-Mora and Antonio Miralles
Economic Journal, 131, 635, April 2021.
Abstract: This paper embeds the problem of public school choice design in a model with local provision of education. We define cardinal (student) segregation as that which emerges when families with identical ordinal preferences submit different rankings of schools. We characterize conditions on preferences and technology that generate cardinal segregation across public schools when the children are allocated to schools using the Boston Mechanism (BM). If risk aversion over educational achievement is smaller for better-off types, and there is sufficient vertical differentiation of schools, any equilibrium with BM will display cardinal segregation. Transportation costs facilitate the emergence of segregation. Competition from private schools promotes segregation as well and, in the process, the best public schools become more elitist. We also examine the Deferred Acceptance mechanism, which is resilient to cardinal segregation.
[Paper in PDF, Online Appendix, video]
Random Assignments and Outside Options
Joint with Francisco Martinez-Mora and Antonio Miralles
Social Choice and Welfare, 57, March 2021.
Abstract: Most environments where assignment mechanisms (possibly random) are used are such that participants have outside options. For instance private schools and private housing are options that participants in a public choice or public housing assignment problems may have. We postulate that, in cardinal mechanisms, chances inside the assignment process could favor agents with better outside options. By imposing a Robustness To Outside Options (RTOO) condition, we conclude that, on the universal domain of cardinal preferences, any mechanism must be (interim) ordinal.
[Paper in PDF]
Structural Estimation of a Model of School Choices: the Boston Mechanism vs. Its Alternatives
Joint with Chao Fu and Maia Guell
Journal of Political Economy, Volume 128, February 2020
Abstract: We model household choice of schools under the Boston mechanism (BM) and develop a new method, applicable to a broad class of mechanisms, to fully solve the choice problem even if it is infeasible via the traditional method. We estimate the joint distribution of household preferences and sophistication types using administrative data from Barcelona. Counterfactual policy analyses show that a change from BM to the Deferred Acceptance mechanism would decrease average welfare by 1,020 euros, while a change to the top trading cycles mechanism would increase average welfare by 460 euros.
A Review on “Basic Income: A Radical Proposal for a Free Society and a Sane Economy”, by Phillipe Van Paris and Yannick Vanderborght
Joint with Sabine Flamand
Journal of Economic Literature, Volumen LVII, Number 3, September 2019
[Paper in PDF]
Grading on a Curve: When Having Good Peers is not Good
Joint with Annalisa Loviglio
Economics of Education Review, Volume 73, December 2019
Abstract: Student access to education levels, tracks or majors is usually determined by their previous performance, measured either by internal exams, designed and graded by teachers in school, or external exams, designed and graded by central authorities. We say teachers grade on a curve whenever having better peers harms the evaluation obtained by a given student. We use rich administrative records from public schools in Catalonia to provide evidence that teachers indeed grade on a curve, leading to negative peer e ects. This puts forth a source of distortion that may arise in any system that uses internal grades to compare students across schools and classes. We nd suggestive evidence that school choice is impacted only the year when internal grades matter for future prospects.
[Paper in PDF]
Priorities in School Choice: The Case of the Boston Mechanism in Barcelona
Joint with Maia Guell
Journal of Public Economics, Volume 163, July 2018
Abstract: The Boston mechanism is a school allocation procedure that is widely used around the world and has been criticized for its incentive problems. In order to resolve overdemands for a given school, most often priority is given to families living in the neighborhood of the school. Using a very rich data set on school applications for the case of the Boston mechanism in Barcelona, we exploit an unexpected change in the denition of neighborhood. This change allows us to identify that a large fraction of families not only does not report preferences truthfully, but ranks first high priority schools, neighborhood schools in this case. Additional data on school enrollment decisions and census data shows that some seemingly unsophisticated parents are high income families that can rank hard-to-get schools because they can aord the outside option of a private school in case they do not get in. This sheds light on important inequalities beyond parents' lack of sophistication found in the literature.
Gender Differences in Responses to Big Stakes
Joint with Ghazala Azmat and Nagore Iriberri
Journal of the European Economic Association Issue 14-6, December 2016
Abstract: In the psychology literature, "choking under pressure" refers to a behavioral response to an increase in the stakes. In a natural experiment, we study the gender difference in performance resulting from changes in stakes. We use detailed information on the performance of high-school students and exploit the variation in the stakes of tests, which range from 5% to 27% of the final grade. We find that female students outperform male students relatively more when the stakes are low. The gender gap disappears in tests taken at the end of high school, which count for 50% of the university entry grade.
[Paper in PDF, VOXeu - CEP [Link & article in PDF]
Maturity and School Outcomes in an Inflexible System: Evidence from Catalonia
Joint with Annalisa Loviglio
Journal of the Spanish Economic Association, Volume 11, March 2020
Abstract: Having a unique cut-off to determine when children can access school induces a large heterogeneity in maturity to coexist in a classroom. We use rich administrative data of the universe of public schools in Catalonia to show that: 1) Relatively younger children do significantly worse both in tests administered at the school level and at the regional level, and they experience greater retention. 2) These effects are homogeneous across SES and significant across the whole distribution of performance. 3) Younger children in our data exhibit higher dropout rates and chose the academic track in secondary school less often. 4) Younger children are more frequently diagnosed with learning disorders.
[Paper in PDF]
Alfred Marshall's Cardinal Theory of Value: The Strong Law of Demand
Joint with Donald J. Brown
Economic Theory Bulletin Volume 2, 65-76, January 2014
Abstract: We show that all the fundamental properties of competitive equilibrium in Marshall’s cardinal theory of value, as presented in Note XXI of the mathematical appendix to his Principles of Economics (1890), derive from the Strong Law of Demand. That is, existence, uniqueness, optimality, and global stability of equilibrium prices with respect to tatonnement price adjustment follow from the cyclical monotonicity of the market demand function in the Marshallian general equilibrium model.
[Paper in PDF]
Cowles Foundation Discussion Paper #1399, Cowles Foundation for Research in Economics, Yale University.
The Incentive Effects of Affirmative Action in a Real-Effort Tournament
Joint with Joerg Franke Pedro Rey-Biel
Journal of Public Economics Volume 98, 15-31, February 2013
Abstract: Affirmative action policies bias tournament rules in order to provide equal opportunities to a group of competitors who have a disadvantage they cannot be held responsible for. Its implementation affects the underlying incentive structure which might induce lower performance by participants, and additionally result in a selected pool of tournament winners that is less efficient. In this paper,we study the empirical validity of such concerns in a case where the disadvantage affects capacities to compete. We conducted real-effort tournaments between pairs of children from two similar schools who systematically differed in how much training they received ex-ante on the task at hand. Contrary to the expressed concerns, our results show that the implementation of affirmative action did not result in a significant performance loss for either advantaged or disadvantaged subjects; instead it rather enhanced the performance for a large group of participants. Moreover, affirmative action resulted in a more equitable tournament winner pool where half of the selected tournament winners came from the originally disadvantaged group. Hence, the negative selection effects due to the biased tournament rules were (at least partially) offset by performance enhancing incentive effects.
[Paper in PDF]
A Comment On: School Choice: An Experimental Study
Joint with Guillaume Haeringer and Flip Klijn
Journal of Economic Theory Volume 146, Number 1, January 2011
Abstract: We show that one of the main results in Chen and Sonmez (J. Econ. Th., 2006, 2008) does no longer hold when the number of recombinations is sufficiently increased to obtain reliable conclusions. No school choice mechanism is significantly superior in terms of efficiency.
[Paper in PDF]
Constrained School Choice: An Experimental Study
Joint with Guillaume Haeringer and Flip Klijn
American Economic Review Volume 100, Number 4, September 2010
Abstract: The literature on school choice assumes that families can submit a preference list over all the schools they want to be assigned to. However, in many real-life instances families are only allowed to submit a list containing a limited number of schools. Subjects' incentives are drastically affected, as more individuals manipulate their preferences. Including a safety school in the constrained list explains most manipulations. Competitiveness across schools play an important role. Constraining choices increases segregation and affects the stability and efficiency of the final allocation. Remarkably, the constraint reduces significantly the proportion of subjects playing a dominated strategy.
[Paper in PDF]
Decentralizing Equality of Opportunity
International Economic Review Volume 50, Number 1, February 2009
Abstract: In a global justice problem, equality of opportunity is satisfied if individual well-being is independent of exogenous irrelevant characteristics. Policymakers, however, address questions involving local justice problems. We interpret a collection of local justice problems as the decentralized global justice problem. We show that controlling for effort locally, which is not required by the global justice objective, is sufficient for decentralizing equality of opportunity. Moreover, under some conditions, equalizing rewards to effort is not only sufficient but necessary. This implies in particular that most affirmative action policies may not contribute to providing equality of opportunity since they do not control for effort.
[Paper in PDF]
The Nonparametric Approach to Applied Welfare Analysis
Joint with Donald J. Brown
Economic Theory Volume 31, Number 1, April 2007
Abstract: Changes in total surplus are traditional measures of economic welfare. We propose necessary and sufficient conditions for rationalizing individual and aggregate consumer demand data with individual quasilinear and homothetic utility functions. Under these conditions, consumer surplus is a valid measure of consumer welfare. For nonmarketed goods, we propose necessary and sufficient conditions on input market data for efficient production, i.e. production at minimum cost. Under these conditions we derive a cost function for the nonmarketed good, where producer surplus is the area above the marginal cost curve.
[Paper in PDF]
Publications in other disciplines
Gender Disparities in Child Custody Sentencing in Spain: a Data Driven Analysis
Joint with Julia Riera, David Solans, Marzieh Karimi-Haghighi and Carlos Castillo
To be presented at ICAIL 2023.
In our work, we investigate biases in judicial decisions using data analytics. Specifically, we are interested in analyzing the impact of the gender of both the judge and the plaintiff on the probability
of winning a case. With this aim, we analyze a dataset comprising information from over one thousand second-instance appeals for child custody in Spain. Our results indicate significant differences in
how legal arguments and facts are utilized in the final sentences, depending on the gender of the plaintiff. We also examine the impact of the requested type of custody (sole or joint) on the probability of winning a case, with a focus on its relationship to the plain- tiff’s gender. Moreover, our analysis reveals statistically significant differences in the winning probability of a case depending on the judge’s gender. To further understand these findings, we conduct additional analysis to establish the causal relationship between the judge’s gender and the probability of winning, revealing weak but consistent patterns. Our research provides a consistent methodol- ogy for evaluating biases in judicial systems and offers intriguing insights into the context of child custody in Spain.
[Paper in PDF]
Comparing equity and effectiveness of different algorithms in an application for the room rental market
Joint with David Solans, Francesco Fabri, Carlos Castillo and Francsco Bonchi
Proceedings of the 2021 AAAI/ACM Conference on AI, Ethics, and Society.
Abstract: Machine Learning (ML) techniques have been increasingly adopted by the real estate market in the last few years. Applications include, among many others, predicting the market value of a property or an area, advanced systems for managing marketing and ads campaigns, and recommendation systems based on user preferences. While these techniques can provide important benefits to the business owners and the users of the platforms, algorithmic biases can result in inequalities and loss of opportunities for groups of people who are already disadvantaged in their access to housing. In this work, we present a comprehensive and independent algorithmic evaluation of a recommender system for the real estate market, designed specifically for finding shared apartments in metropolitan areas. We were granted full access to the internals of the platform, including details on algorithms and usage data during a period of 2 years.
We analyze the performance of the various algorithms which are deployed for the recommender system and asses their effect across different population groups. Our analysis reveals that introducing a recommender system algorithm facilitates finding an appropriate tenant or a desirable room to rent, but at the same time, it strengthen performance inequalities between groups, further reducing opportunities of finding a rental for certain minorities.
[Paper in PDF]
Non-published working papers
Rationalizing and Curve-Fitting Demand Data with Quasilinear Utilities
Joint with Donald J. Brown
Abstract: In the empirical and theoretical literature a consumer's utility function is often assumed to be quasilinear. In this paper we provide necessary and sufficient conditions for testing if the consumer acts as if she is maximizing a quasilinear utility function over her budget set. If the consumer's choices are inconsistent with maximizing a quasilinear utility function over her budget set, then we compute the "best" quasilinear rationalization of her choices.
[Paper in PDF, Cowles Foundation Discussion Paper #1399R, Cowles Foundation for Research in Economics, Yale University.]
Caterina Calsamiglia, IPEG, revised August 2021