IGIER fellows and affiliates publish books and articles in academic journals. Their current research projects are featured in the Working Paper series.
In a recent paper, Lin & Palfrey (2022, revised 2023) developed a theory of cognitive hierarchies (CH) in sequential games and observed that this solution concept in not reduced-normal-form invariant. In this note I qualify this observation by showing that the CH model is normal-form invariant, and that the diferences arising from the application of the CH model to the reduced normal form depend only on how randomization by level-0 types is modeled. Indeed, while the uniform behavior strategy in the extensive form yields the uniform mixed strategy in the normal form, the latter does not correspond to the uniform randomization in the reduced normal form, because different reduced strategies may correspond to sets of equivalent strategies with different cardinalities. I also note that results in the literature on transformations of sequential games imply that the sequential CH model of Lin & Palfrey is in variant to the interchanging of essentially simultaneous moves, but it is not invariant to coalescing of moves(and, of course, its inverse, sequential agents splitting).Finally, I note that the independence of ex ante beliefs about the level-types of co-players is preserved by updated beliefs conditional on information sets in all games with observable deviators.
We study whether a better knowledge of the functioning of pay-as-you-go pension systems and recent demographic trends affects natives’ attitudes towards immigration. In two online experiments conducted in Italy and Spain, we randomly treated participants with a video explaining how, in pay-as-you-go systems, the payment of current pensions depends on the contributions paid by current workers. The video also informs participants about population aging trends in their countries. The treatment increases knowledge of pay-as-you-go systems and future demographic trends for all participants. However, it improves attitudes towards migrants only for treated participants who do not support populist and anti-immigrant parties.
We document the spiral of populism in Europe and the direct and indirect role of economic insecurity shocks. Using survey data on individual voting, we make two contributions to the literature, namely: (1) Economic insecurity shocks have a significant impact on the populist vote share, directly as demand for protection, and
indirectly through the induced changes in trust and attitudes; (2) A key consequence of increased economic insecurity is a drop in turnout. The impact of this largely neglected turnout effect is substantial: conditional on voting, when economic insecurity increases almost 40% of the induced change in the vote for a populist party comes from the turnout channel.
This paper empirically shows that the imbalance between an ethnic group’s political and military power is crucial to understanding the likelihood that such a group engages in a conflict. We develop a novel measure of a group’s military power by combiningmachine learning techniques with rich data on ethnic group characteristics and
outcomes of civil conflicts in Africa and theMiddle East. We couple thismeasure with available indicators of an ethnic group’s political power as well as with a novel proxy based on information about the ethnicity of cabinet members. We find that groups characterized by a highermismatch betweenmilitary and political power are between 30% and 50% more likely to engage in a conflict against their government depending on the specification used. We also find that the effects of power mismatch are nonlinear, which is in agreement with the predictions of a simplemodel that accounts for the cost of conflict. Moreover, our results suggest that high-mismatched groups are typically involved in larger and centrist conflicts. The policy implication is that powersharing recommendations and institutional design policies for peace should consider primarily the reduction of power mismatches between relevant groups, rather than focusing exclusively on equalizing political power in isolation.
We analyze the infinite repetition with imperfect feedback of a simultaneous or sequential game, assuming that players are strategically sophisticated---but possibly impatient---expected-utility maximizers. Sophisticated strategic reasoning in the repeated game is combined with belief updating to provide a foundation for a refinement of self-confirming equilibrium. In particular, we model strategic sophistication as rationality and common strong belief in rationality. Then, we combine belief updating and sophisticated reasoning to provide sufficient conditions for a kind of learning--that is, the ability, in the limit, to exactly forecast the sequence of future observations--thus showing that impatient agents end up playing a sequence of self-confirming equilibria in strongly rationalizable conjectures of the one-period game. We also provide a converse of this result. Irrespective of whether individuals value the future, if they are able to learn then they will play in the limit a self-confirming equilibrium in strongly rationalizable conjectures of the continuation (infinitely repeated) game.
How do people form beliefs about novel risks, with which they have little or no experience? Motivated by survey data we collected in 2020, which showed that beliefs about Covid’s lethality depended on a range of personal experiences in unrelated domains, we build a model based on the psychology of selective memory. When a person thinks about an event, different experiences compete for retrieval, and retrieved experiences are used to simulate the event based on how similar they are to it. The model yields predictions on how experiences interfere with each other in recall and how non domain-specific experiences bias beliefs based on their similarity to the assessed event. We test these predictions using data from our Covid survey and from a primed-recall experiment about cyberattack risk. Experiences and their measured similarity to the cued event successfully help explain beliefs, with patterns consistent with our theory. Our approach offers a new, structured way to study and jointly account for systematic biases and substantial belief heterogeneity.
We construct an index of long term expected earnings growth for S&P500 firms and show that it has remarkable power to jointly predict future errors in these expectations and stock returns, in both the aggregate market and the cross section. The evidence supports a mechanism whereby good news cause investors to become too optimistic about long term earnings growth, for the market as a whole but especially for a subset of firms. This leads to inflated stock prices and, as beliefs are systematically disappointed, to subsequent low returns in the aggregate market and for the subset of firms. Overreaction of long term expectations helps resolve or asset pricing puzzles without time series or cross-sectional variation in required returns.
We document two new facts about the distributions of answers in famous statistical problems: they are i) multi-modal and ii) unstable with respect to irrelevant changes in the problem. We offer a model in which, when solving a problem, people represent each hypothesis by attending “bottom up” to its salient features while neglecting other, potentially more relevant, ones. Only the statistics associated with salient features are used, others are neglected. The model unifies Gambler’s Fallacy, its variation by sample size, under- and overreaction in inference, and insensitivity to multiple signals, all as a byproduct of selective attention. The model also makes new predictions on how controlled changes in the salience of specific features should jointly shape measured attention and biases. We test and confirm these predictions experimentally, including by measuring attention and documenting novel biases predicted by the model. Bottom-up attention to features emerges as a unifying framework for biases conventionally explained using a variety of stable heuristics or distortions of the Bayes rule.
This handbook chapter studies how natural resource wealth can in many contexts fuel armed conflict. Starting from a simple theoretical model, we stress the role of geography and power mismatch in the so called "natural resource curse". Drawing on recent empirical evidence, the importance of resource abundance, asymmetry and capital-intensiveness is highlighted, alongside local grievances and international interventions. We propose a series of evidence-driven policy conclusions, ranging from "smart green transition" and democratic institution building over labor-market intervention to a series of specific policies requiring international coordination.
This paper discusses the historical and social origins of the bifurcation in the political institutions of China and Western Europe. An important factor, recognized in the literature, is that China centralized state institutions very early on, while Europe remained politically fragmented for much longer. These initial differences, however, were amplified by the different social organizations (clans in China, corporate structures in Europe) that spread in these two societies at the turn of the first millennium AD. State institutions interacted with these organizations, and were shaped and influenced by this interaction. The paper discusses the many ways in which corporations contributed to the emergence of representative institutions and gave prominence to the rule of law in the early stages of state formation in Europe, and how specific features of lineage organizations contributed to the consolidation of the Imperial regime in China.
This paper explores the tradeoff between competition and financial inclusion given by the vertical integration between mobile network and money operators. Joining novel data on mobile money fees built through the WayBack machine, with sources on network coverage and financials, we examine the staggering across African operators and countries of platform interoperability – a policy that promotes transactions and competition across mobile money operators. Our findings show that interoperability lowers mobile money fees and reduces network coverage and mobile towers, especially in rural and poor districts. Interoperability also results in a decline in various survey metrics of financial inclusion.
We compute new estimates for Total Factor Productivity (TFP) growth in five European countries and in the United States. Departing from standard methods, we account for positive profits and use firm surveys to proxy for unobserved changes in factor utilization. These novelties have a major impact in Europe, where our estimated TFP growth series are less volatile and less cyclical than the ones obtained with standard methods. Based on our approach, we provide annual industry-level and aggregate TFP series, as well as the first estimates of utilization-adjusted quarterly TFP growth in Europe.
JEL Codes: E01, E30, O30, O40
We study the stabilizing role of benefit extensions. We develop a tractable quantitative model with heterogeneous agents, search frictions, and nominal rigidities. The model allows for a stabilizing aggregate demand channel and a destabilizing labor market channel. We characterize each channel analytically and find that aggregate demand effects quantitatively prevail in the US. When feeding-in estimated shocks, the model tracks unemployment in the two most recent downturns. We find that extensions lowered unemployment by a maximum of 0.35 pp in the Great Recession, while the joint stabilizing effect of extensions and benefit compensation peaked at 1.08 pp in the pandemic.
We offer a theory of changing dimensions of political polarization based on endogenous social identity. We formalize voter identity and stereotyped beliefs as in Bonomi et al. (2021), but add parties that compete on policy and also spread or conceal group stereotypes to persuade voters. Parties are historically connected to different social groups, whose members are more receptive to the ingroup party messages. An endogenous switch from class to cultural identity accounts for three major observed changes: i) growing conflict over cultural issues between voters and between parties, ii) dampening of political conflict over redistribution, despite rising inequality, and iii) a realignment of lower class voters from the left to the right. The incentive of parties to spread stereotypes is a key driver of identity-based polarization. Using survey data and congressional speeches we show that - consistent with our model - there is evidence of i) and ii) also in the voting realignment induced by the ”China Shock” (Autor et al. 2020).
I show that offering monetary rewards to whistleblowers can backfire as a moral aversion to being paid for harming others can reverse the effect of financial incentives. I run a field experiment with employees of the Afghan Ministry of Education, who are asked to confidentially report on their colleagues’ attendance. I use a two-by-two design, randomizing whether or not reporting absence carries a monetary incentive as well as the perceived consequentiality of the reports. In the consequential treatment arm, where employees are given examples of the penalties that might be imposed on absentees, 15% of participants choose to denounce their peers when reports are not incentivized. In this consequential group, rewards backfire: only 10% of employees report when denunciations are incentivized. In the non-consequential group, where participants are guaranteed that their reports will not be forwarded to the government, only 6% of employees denounce absence without rewards. However, when moral concerns of harming others are limited through the guarantee of non-consequentiality, rewards do not backfire: the incentivized reporting rate is 12%
Debt moratoria that allow borrowers to postpone loan payments are a frequently used tool intended to soften the impact of economic crises. We conduct a nationwide experiment with a large consumer lender in India to study how debt forbearance offers affect loan repayment and banking relationships. In the experiment, borrowers receive forbearance offers that are presented either as an initiative of their lender or the result of government regulation. We find that delinquent borrowers who are offered a debt moratorium by their lender are 4 percentage points (7 percent) less likely to default on their loan, while forbearance has no effect on repayment if it is granted by the regulator. Borrowers who are offered forbearance by their lender also have higher demand for future interactions with the lender: in a follow-up experiment conducted several months after the main intervention, demand for a non-credit product offered by the lender is 10 percentage points (27 percent) higher among customers who were offered repayment flexibility by the lender than among customers who received a moratorium offer presented as an initiative of the regulator. Overall, our results suggest that, rather than generating moral hazard, debt forbearance can improve loan repayment and support the creation of longer-term banking relationships not only for liquidity but also for relational contracting reasons. This provides a rationale for offering repayment flexibility even in settings where lenders are not required to provide forbearance.
Real-world contests are inherently uncertain since the player who exerts the highest effort can still lose. In this paper, I consider a general asymmetric incomplete information contest model with a nonparametric distribution of uncertainty in the contest success function. It generalizes all-pay auctions, Tullock contests, and rank-order tournaments with two asymmetric players. Uncertainty in the contest success function summarizes other factors that influence the contest win outcome apart from the efforts of the players, such as, for example, players’ reputation or luck. First, I nonparametrically identify and estimate the distribution of uncertainty using the information on contest win outcomes and efforts. Next, I nonparametrically identify and estimate the distributions of the players’ costs of exerting effort. The model provides a method to disentangle two sources of player’s advantage: asymmetry in the costs’ distributions and the effect of the uncertainty distribution on the winning probability. As an empirical example, I apply the model to the U.S. House of Representatives elections.
We study mean-variance approximations for a large class of preferences. Compared to the standard mean-variance approximation that only features a risk variability term, a novel index of variability appears. Its neglect in an empirical estimation may result in puzzling in ated risk terms of standard mean-variance approximations.
We consider a model of a limit order book and determine the optimal tick size set by a social planner who maximizes the welfare of market participants. In a 2-period model where only two agents arrive sequentially, the tick size is a friction that constrains investors to use discrete price grids, and as a consequence the optimal tick size is equal to zero. However, in a model with sequential arrival of more than two investors who can endogenously either take liquidity or supply liquidity by undercutting or queuing behind existing orders, the tick size is positive: it is a strategic tool a social planner uses to optimally affect the choice made by investors between liquidity demand and supply. In addition, the optimal tick size is a function both of the value of the asset and of trading volume. The policy implication of such findings is that the European tick size regime and the “Intelligent Ticks” Nasdaq proposal dominate Reg. NMS Rule 612 that formalizes the tick size regime for the U.S. markets. Using data from the U.S. and the European markets we test our model’s empirical predictions.
We study how individuals comment on political news posted on Reddit’s main political forum during the 2016 US Presidential Election. We show that partisan users behave very differently from independents if the news is bad for a candidate. They avoid commenting unfavorable polls and scandals on their favorite candidate, but seek such news on its opponent. When they do comment bad news on their favorite candidate, they try to rationalize it, display a more negative sentiment, and are more likely to cite scandals of the opponent. This behavior is consistent with motivated reasoning, and with the predictions of a model of costly attention, where the cost of attention depends on whether the news is pleasant or unpleasant.
We explore how business groups use internal labor markets (ILMs) in response to changing economic conditions. We show that following the exit of a large industry competitor, groupaffiliated firms expand and gain market share by increasing their reliance on the ILM to ensure swift hiring, especially of technical managers and skilled blue collar workers. The ability to take advantage of this shock to growth opportunities is greater in firms with closer access to their affiliates’ human capital, as geographical proximity facilitates employee relocations across units. Overall, our findings point to the ILM as a prominent mechanism making affiliation with a business group valuable at times of change. For the ILM to perform its role in the face of industry shocks, group sectoral diversification must be combined with geographical proximity between affiliates.
We study the implications of employment targets on firm dynamics during the privatization of the East German economy. Exploiting novel contract-level data, we document three stylized facts. First, the policy distorted firm size choices and generated bunching of firms around their committed employment target. Second, exploiting heterogeneous labor preferences of privatizers, we show that assigning tight commitments to firms causes an increase in employment growth and leads to higher productivity growth. Finally, tighter commitments also result in significant costs by leading to increased firm exit. We interpret these results through the lens of a dynamic model with endogenous productivity growth at the firm level. The model highlights that while tight commitments distort the employment decision statically and lead to a higher exit probability, they also induce a “catch-up” increase in productivity growth. This is because although firm profits are lower under tight commitments, marginal profits with respect to productivity are higher. We calibrate the model to our data and find that the policy lead to a 3 percentage points higher aggregate TFP growth thanks to the productivity improvements of firms with tight contracts.
We investigate the impact of prices on ratings using Airbnb data. We theoretically illustrate two opposing channels: higher prices reduce the value for money, worsening ratings, but they increase the taste-based valuation of the average traveler, improving ratings. Results from panel regressions and a regression discontinuity design suggest a dominant value-for-money effect. In line with our model, hosts strategically complement lower prices with higher effort more when ratings are relatively low. Finally, we provide evidence that, upon entry, strategic hosts exploit the dominant value-for-money effect. The median entry discount of seven percent improves medium-run monthly revenues by three percent.
We propose that the mathematical representation of situations of strategic interactions, i.e., of games, should separate the description of the rules of the game from the description of players’ personal traits. Yet, we note that the standard extensive-form partitional representation of information in sequential games does not comply with this separation principle. We offer an alternative representation that extends to all (finite) sequential games the approach adopted in the theory of repeated games with imperfect monitoring, that is, we describe the flow of information accruing to players rather than the stock of information retained by players, as encoded in information partitions. Mnemonic abilities can be represented independently of games. Assuming that players have perfect memory, our flow representation gives rise to information partitions satisfying perfect recall. Different combinations of rules about information flows and of players mnemonic abilities may give rise to the same information partition . All extensive-form representations with information partitions, including those featuring absentmindedness, can be generated by some such combinations.
We provide two characterizations, one axiomatic and the other neuro-computational, of the dependence of choice probabilities on deadlines, within the widely used softmax representation (see below picture) where pt (a; A) is the probability that alternative a is selected from the set A of feasible alternatives if t is the time available to decide, is a time dependent noise parameter measuring the unit cost of information, u is a time independent utility function, and a is an alternative-specific bias that determines the initial choice probabilities and possibly reflects prior information. Our axiomatic analysis provides a behavioral foundation of softmax (also known as Multinomial Logit Model when a is constant). Our neuro-computational derivation provides a biologically inspired algorithm that may explain the emergence of softmax in choice behavior. Jointly, the two approaches provide a thorough understanding of soft-maximization in terms of internal causes (neurophysiological mechanisms) and external effects (testable implications).
Journal of Economic Literature Classification Numbers: C70, D83
Journal of Economic Literature Classification Numbers: C70, D83
We evaluate linear stochastic discount factor models using an ex-post portfolio metric: the realized out-of-sample Sharpe ratio of mean-variance portfolios backed by alternative linear factor models. Using a sample of monthly US portfolio returns spanning the period 1968-2016, we find evidence that multifactor linear models have better empirical properties than the CAPM, not only when the cross-section of expected returns is evaluated in-sample, but also when they are used to inform one-month ahead portfolio selection. When we compare portfolios associated to multifactor models with mean-variance decisions implied by the single-factor CAPM, we document statistically significant differences in Sharpe ratios of up to 10 percent. Linear multifactor models that provide the best in-sample fit also yield the highest realized Sharpe ratios.
The Italian civil war and the Nazi occupation of Italy occurred at a critical juncture, just before the birth of a new democracy. We study the impact of these traumatic events by exploiting geographic heterogeneity in the duration and intensity of civil war, and the persistence of the battlefront along the "Gothic line" cutting through Northern-Central Italy. We find that the Communist Party gained votes in postwar elections where the Nazi occupation lasted longer, mainly at the expense of centrist parties. This effect persists until the late 1980s and appears to be driven by equally persistent changes in political attitudes.
We provide both an axiomatic and a neuropsychological characterization of the dependence of choice probabilities on time in the softmax (or Multinomial Logit Process) form (see below picture) MLP is the most widely used model of preference discovery in all fields of decision making, from Quantal Response Equilibrium to Discrete Choice Analysis, from Psychophysics and Neuroscience to Combinatorial Optimization. Our axiomatic characterization of softmax permits to empirically test its descriptive validity and to better understand its conceptual underpinnings as a theory of agents'rationality. Our neuropsychological foundation provides a computational model that may explain softmax emergence in human behavior and that naturally extends to multialternative choice the classical Diffusion Model paradigm of binary choice. These complementary approaches provide a complete perspective on softmaximization as a model of preference discovery, both in terms of internal (neuropsychological) causes and external (behavioral) effects.
What explains the formation and decay of clusters of creativity? We match data on notable
individuals born in Europe between the XIth and the XIXth century with historical city data.
The production and attraction of creative talent is associated with city institutions that protected economic and political freedoms and promoted local autonomy. Instead, indicators of local economic conditions such as city size and real wages, do not predict creative clusters. We also show that famous creatives are spatially concentrated and clustered across disciplines, that their spatial mobility has remained stable over the centuries, and that creative clusters are persistent but less than population.