The Basics of International Trade: A Classroom Experiment

We introduce a simple web-based classroom experiment in which students learn the Ricardian model of international trade. Students are assigned to countries and then make individual production, trade and consumption decisions. The analysis of experimental data introduces students to the concepts of absolute and comparative advantage, relative prices, production possibility frontier, specialization, gains from trade, utility maximization and general equilibrium. Students learn about the relationship between individual decision-making and aggregate economic activity. The associated software, Ricardian Explorer, is easy to setup and requires minimal preparation time for instructors. The game is developed as a tool to complement courses in international trade, but it can be used in introductory and intermediate microeconomics courses as well. The analysis of teaching effectiveness has demonstrated that integration of this experiment in the curriculum enhances student learning.Absolute advantage, comparative advantage, specialization, production possibility frontier, gains from trade, utility maximization, general equilibrium, classroom experiments

Getting Closer or Drifting Apart

Advances in communication and transportation technologies have the potential to bring people closer together and create a "global village." However, they also allow heterogeneous agents to segregate along special interests, which gives rise to communities fragmented by type rather than by geography. We show that lower communication costs should always decrease separation between individual agents even as group-based separation increases. Each measure of separation is pertinent for distinct types of social interaction. A group-based measure captures the diversity of group preferences that can have an impact on the provision of public goods. While an individual measure correlates with the speed of information transmission through the social network that affects, for example, learning about job opportunities and new technologies. We test the model by looking at coauthoring between academic economists before and during the rise of the Internet in the 1990s.Economic

Why Beauty Matters

We decompose the beauty premium in an experimental labor market where “employers” determine wages of “workers” who perform a maze-solving task. This task requires a true skill which we show to be unaffected by physical attractiveness. We find a sizable beauty premium and can identify three transmission channels: (a) physically attractive workers are more confident and higher confidence increases wages; (b) for a given level of confidence, physically attractive workers are (wrongly) considered more able by employers; (c) controlling for worker confidence, physically attractive workers have oral skills (such as communication and social skills) that raise their wages when they interact with employers. Our methodology can be adopted to study the sources of discriminatory pay differentials in other settings.Economic

What Do We Expect from Our Friends?

We conduct a field experiment in a large real-world social network to examine how subjects expect to be treated by their friends and by strangers who make allocation decisions in modified dictator games. While recipients’ beliefs accurately account for the extent to which friends will choose more generous allocations than strangers (i.e. directed altruism), recipients are not able to anticipate individual differences in the baseline altruism of allocators (measured by giving to an unnamed recipient, which is predictive of generosity towards named recipients). Recipients who are direct friends with the allocator, or even recipients with many common friends, are no more accurate in recognizing intrinsically altruistic allocators. Recipient beliefs are significantly less accurate than the predictions of an econometrician who knows the allocator’s demographic characteristics and social distance, suggesting recipients do not have information on unobservable characteristics of the allocator.dictator games, beliefs, baseline altruism, directed altruism, social networks

Directed Altruism and Enforced Reciprocity in Social Networks: How Much is A Friend Worth?

We conduct field experiments in a large real-world social network to examine why decision makers treat friends more generously than strangers. Subjects are asked to divide surplus between themselves and named partners at various social distances, where only one of the decisions is implemented. In order to separate altruistic and future interaction motives, we implement an anonymous treatment where neither player is told at the end of the experiment which decision was selected for payment and a non-anonymous treatment where both players are told. Moreover, we include both games where transfers increase and decrease social surplus to distinguish between different future interaction channels including signaling one's generosity and enforced reciprocity, where the decision maker treats the partner to a favor because she can expect it to be repaid in the future. We can decompose altruistic preferences into baseline altruism towards any partner and directed altruism towards friends. Decision makers vary widely in their baseline altruism, but pass at least 50 percent more surplus to friends compared to strangers when decision making is anonymous. Under non-anonymity, transfers to friends increase by an extra 24 percent relative to strangers, but only in games where transfers increase social surplus. This effect increases with density of the network structure between both players, but does not depend on the average amount of time spent together each week. Our findings are well explained by enforced reciprocity, but not by signaling or preference-based reciprocity. We also find that partners' expectations are well calibrated to directed altruism, but that they ignore decision makers' baseline altruism. Partners with high baseline altruism have friends with higher baseline altruism and are therefore treated better.

What Do We Expect from Our Friends?

We conduct a field experiment in a large real-world social network to examine how subjects expect to be treated by their friends and by strangers who make allocation decisions in modified dictator games. While recipients beliefs accurately account for the extent to which friends will choose more generous allocations than strangers (i.e. directed altruism), recipients are not able to anticipate individual differences in the baseline altruism of allocators (measured by giving to an unnamed recipient, which is predictive of generosity towards named recipients). Recipients who are direct friends with the allocator, or even recipients with many common friends, are no more accurate in recognizing intrinsically altruistic allocators. Recipient be- liefs are significantly less accurate than the predictions of an econometrician who knows the allocators demographic characteristics and social distance, suggesting recipients do not have information on unobservable characteristics of the allocator.dictator games, beliefs, baseline altruism, directed altruism, social networks

Directed Altruism and Enforced Reciprocity in Social Networks

We conduct online field experiments in large real-world social networks in order to decompose prosocial giving into three components: (1) baseline altruism toward randomly selected strangers, (2) directed altruism that favors friends over random strangers, and (3) giving motivated by the prospect of future interaction. Directed altruism increases giving to friends by 52 percent relative to random strangers, while future interaction effects increase giving by an additional 24 percent when giving is socially efficient. This finding suggests that future interaction affects giving through a repeated game mechanism where agents can be rewarded for granting efficiency enhancing favors. We also find that subjects with higher baseline altruism have friends with higher baseline altruism.modified dictator games, directed altruism, enforced reciprocity, social networks

Managing Self-Confidence: Theory and Experimental Evidence

Evidence from social psychology suggests that agents process information about their own ability in a biased manner. This evidence has motivated exciting research in behavioral economics, but has also garnered critics who point out that it is potentially consistent with standard Bayesian updating. We implement a direct experimental test. We study a large sample of 656 undergraduate students, tracking the evolution of their beliefs about their own relative performance on an IQ test as they receive noisy feedback from a known data-generating process. Our design lets us repeatedly measure the complete relevant belief distribution incentive-compatibly. We find that subjects (1) place approximately full weight on their priors, but (2) are asymmetric, over-weighting positive feedback relative to negative, and (3) conservative, updating too little in response to both positive and negative signals. These biases are substantially less pronounced in a placebo experiment where ego is not at stake. We also find that (4) a substantial portion of subjects are averse to receiving information about their ability, and that (5) less confident subjects are causally more likely to be averse. We unify these phenomena by showing that they all arise naturally in a simple model of optimally biased Bayesian information processing.

Are Risk Attitudes Fixed Factors or Fleeting Feelings?

We investigate the stability of measured risk attitudes over time, using a 13-year longitudinal sample of individuals in the National Longitudinal Survey of Youth 1979. We find that an individual’s risk aversion changes systematically in response to personal economic circumstances. Risk aversion increases with lengthening spells of employment and time out of labor force, and decreases with lengthening unemployment spells. However, the most important result is that the majority of the variation in risk aversion is due to changes in measured individual tastes over time and not to variation across individuals. These findings that measured risk preferences are endogenous and subject to substantial measurement errors suggest caution in interpreting coefficients in models relying on contemporaneous, one-time measures of risk preferences