Syngjoo Choi

By using graphical representations of simple portfolio choice problems, we generate a very rich dataset to study behavior under uncertainty at the level of the individual subject. We test the data for consistency with the maximization hypothesis, and we estimate preferences using a two-parameter utility function based on Faruk Gul (1991). This specification provides a good interpretation of the data at the individual level and can account for the highly heterogeneous behaviors observed in the la

Skin hyperpigmentation is caused by the overproduction of melanin pigment, which is synthesized by the action of tyrosinase. We recently reported that aloesin inhibits tyrosinase activity. The present study was undertaken to test the inhibitory effect of aloesin on pigmentation in human skin after UV radiation. Experimental subjects were UV-irradiated (210 mJ) on the inner forearm. UV-irradiated regions were assigned to four groups: vehicle control, aloesin treated, arbutin treated, and aloesin

Schooling rewards people with labor market returns and nonpecuniary benefits in other realms of life. However, there is no experimental evidence showing that education interventions improve individual economic rationality. We examine this hypothesis by studying a randomized 1-year financial support program for education in Malawi that reduced absence and dropout rates and increased scores on a qualification exam of female secondary school students. We measure economic rationality 4 years after t

We propose a model of posted prices in networks. The model maps traditional concepts of market power, competition, and double marginalization into networks, allowing for the study of pricing in complex structures of intermediation, such as supply chains, transportation and communication networks, and financial brokerage. We provide a complete characterization of equilibrium prices. Our experiments complement our theoretical work and point to node criticality as an organizing principle for unders

Revealing Preferences Graphically: An Old Method Gets a New Tool Kit by Syngjoo Choi, Raymond Fisman, Douglas M. Gale and Shachar Kariv. Published in volume 97, issue 2, pages 153-158 of American Economic Review, May 2007

Networks are natural tools for understanding social and economic phenomena. For example, all markets are characterized by agents connected by complex, multilateral information networks, and the network structure influences economic outcomes. In an earlier study, we undertook an experimental investigation of learning in various three-person networks, each of which gives rise to its own learning patterns. In the laboratory, learning in networks is challenging and the difficulty of solving the deci

Individuals living in society are bound together by a social network, the complex of relationships that brings them into contact with other agents. In many social and economic situations, individuals learn by observing the behavior of others in their local environment. This process is called social learning. Learning in incomplete networks, where different agents have different information sets, is especially challenging: because of the lack of common knowledge individuals must draw inferences a

There is a large body of empirical work which studies the influence of network structure on economic outcomes, but these observational studies are subject to identification problems. In the laboratory, by contrast, we can control subjects’ position in the network and their information. This provides an opportunity to test the predictions of network theories and study the effects of variables about which our models have little to say. This chapter surveys network research in experimental economic