Knowledge that Transforms

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The Technology Cycle and Inequality

Review of Economic Studies 2009 76(2), 707-729
Motivated by the observed rise in the trade of technology, I analyse how technology would spread in a frictionless market. In such a world, low-skilled agents prefer to use old technology because it costs less; their skills do not justify the use of frontier technology. The model generates a technology-life cycle of somewhere between 68 and 124 years and per-capita income differential factors between 2.3 and 4.5. The model matches fairly well the cross-section relation between a country's income per capita and the average age of the technologies that its residents use. It is also consistent with aspects of the observed positive relation between income and imports of technology.

Entry and Competition Effects in First-Price Auctions: Theory and Evidence from Procurement Auctions

Review of Economic Studies 2009 76(4), 1397-1429
Motivated by several interesting features of the highway mowing auction data from the Texas Department of Transportation (TDoT), we study three competing procurement auction models with endogenous entry. Our entry and bidding models provide several interesting implications. For the first time, we show that even within an independent private value paradigm, as the number of potential bidders increases, bidders' equilibrium bidding behaviour can become less aggressive, and the expected procurement cost may rise because the “entry effect” is always positive and may dominate the negative “competition effect”. We then develop structural models of entry and bidding corresponding to the three models under consideration, controlling for unobserved auction heterogeneity, and use the recently developed semi-parametric Bayesian estimation method to analyse the data. We select the model that best fits the data, and use the corresponding structural estimates to quantify the “entry effect” and the “competition effect” with regard to the individual bids and the procurement cost.

Moderation in Groups: Evidence from Betting on Ice Break-ups in Alaska

Review of Economic Studies 2009 77(3), 882-913
We use a large sample of guessed ice break-up dates for the Tanana River in Alaska to study differences between outcomes of decisions made by individuals versus groups. We estimate the distribution of guesses conditional on whether they were made by individual bettors or betting pools. We document two major distinctions between the two sets of guesses: (1) the distribution of guesses made by groups of bettors appears to conform more to the distribution of historical break-up dates than the distribution of guesses made by individual bettors, and (2) the distribution for groups has less mass in its tails and displays lower variability than the distribution for individuals. We argue that these two pieces of evidence are consistent with the hypothesis that group decisions are more moderate, either because groups have to reach a compromise when their members disagree or because individuals with extreme opinions are less likely to be part of a group.

Voluntarily Separable Repeated Prisoner's Dilemma

Review of Economic Studies 2009 76(3), 993-1021
Ordinary repeated games do not apply to real societies where one can cheat and escape from partners. We formulate a model of endogenous relationships that a player can unilaterally end and start with a randomly assigned new partner with no information flow. Focusing on two-person, two-action Prisoner's Dilemma, we show that the endogenous duration of partnerships generates a significantly different evolutionary stability structure from ordinary random matching games. Monomorphic equilibria require initial trust building, while a polymorphic equilibrium includes earlier cooperators than any strategy in monomorphic equilibria and is thus more efficient. This is due to the non-linearity of average payoffs.

Do Population Control Policies Induce More Human Capital Investment? Twins, Birth Weight and China's “One-Child” Policy

Review of Economic Studies 2009 76(3), 1149-1174 open access
In this paper, we address the issues of whether reductions in fertility increase human capital investments per child and whether twinning can identify the quantity—quality (Q-Q) trade-off. We show that estimates of the effects of twinning at higher parities on the outcomes of older children in prior studies do not identify family-size effects but are confounded by inter-child allocation effects because of the endowment deficit and close spacing of twins. However, examining the effects of twinning by birth order, net of the effects stemming from the endowment deficit of twins, can provide upper and lower bounds on the trade-off between the family size and average child quality. Our estimates, based on data from China, indicate that an extra child at parity one or at parity two, net of one component of birth-endowment effects associated with birth weight, significantly decreases the schooling progress, the expected college enrolment, grades in school and the assessed health of all children in the family. Despite the evident significant trade-off between number of children and child quality in China, the findings suggest that the contribution of the one-child policy in China to the development of its human capital was modest.

A Truth Serum for Non-Bayesians: Correcting Proper Scoring Rules for Risk Attitudes

Review of Economic Studies 2009 76(4), 1461-1489 open access
Proper scoring rules provide convenient and highly efficient tools for incentive-compatible elicitations of subjective beliefs. As traditionally used, however, they are valid only under expected value maximization. This paper shows how they can be generalized to modern (“non-expected utility”) theories of risk and ambiguity, yielding mutual benefits: users of scoring rules can benefit from the empirical realism of non-expected utility, and analysts of ambiguity attitudes can benefit from efficient measurements using proper scoring rules. An experiment demonstrates the feasibility of our generalization.

Peer Effects and Social Networks in Education

Review of Economic Studies 2009 76(4), 1239-1267
We develop a model that shows that, at the Nash equilibrium, the outcome of each individual embedded in a network is proportional to his/her Katz-Bonacich centrality measure. This measure takes into account both direct and indirect friends of each individual, but puts less weight to his/her distant friends. We then bring the model to the data using a very detailed dataset of adolescent friendship networks. We show that, after controlling for observable individual characteristics and unobservable network specific factors, a standard deviation increase in the Katz-Bonacich centrality increases the pupil school performance by more than 7% of one standard deviation.

Slavery and Other Property Rights1

Review of Economic Studies 2009 76(1), 319-342
The institution of slavery is found mostly at intermediate stages of agricultural development and less often among hunter-gatherers and advanced agrarian societies. We explain this pattern in a growth model with land and labour as inputs in production and an endogenously determined property rights institution. The economy endogenously transits from an egalitarian state with equal property rights to a despotic slave society where the elite own both people and land; thereafter, it endogenously transits into a free labour society, where the elite own the land but people are free.

Strategic Communication with Lying Costs

Review of Economic Studies 2009 76(4), 1359-1395
I study a model of strategic communication between an uninformed Receiver and an informed but upwardly biased Sender. The Sender bears a cost of lying, or more broadly, of misrepresenting his private information. The main results show that inflated language naturally arises in this environment, where the Sender (almost) always claims to be of a higher type than he would with complete information. Regardless of the intensity of lying cost, there is incomplete separation, with some pooling on the highest messages. The degree of language inflation and how much information is revealed depend upon the intensity of lying cost. The analysis delivers a framework to span a class of cheap-talk and verifiable disclosure games, unifying the polar predictions they make under large conflicts of interest. I use the model to discuss how the degree of manipulability of information can affect the trade-off between delegation and communication.

Dynamic Kidney Exchange

Review of Economic Studies 2009 77(1), 372-414 open access
We study how barter exchanges should be conducted through a centralized mechanism in a dynamically evolving agent pool with time- and compatibility-based preferences. We derive the dynamically efficient two-way and multi-way exchange mechanisms that maximize total discounted exchange surplus. Recently several live-donor kidney exchange programmes were established to swap incompatible donors of end-stage kidney disease patients. Since kidney exchange can be modelled as a special instance of our more general model, dynamically efficient kidney exchange mechanisms are derived as corollaries. We make policy recommendations using simulations.