Knowledge that Transforms

Geography and social links shape economic interactions. In industries, schools, and markets, the entire network determines outcomes. This paper analyzes a large class of games and obtains a striking result. Equilibria depend on a single network measure: the lowest eigenvalue. This paper is the first to uncover the importance of the lowest eigenvalue to economic and social outcomes. It captures how much the network amplifies agents' actions. The paper combines new tools—potential games, optimization, and spectral graph theory—to solve for all Nash and stable equilibria and applies the results to R&D, crime, and the econometrics of peer effects.

The Combinatorial Clock Auction (CCA) is an important recent innovation in auction design which has been adopted for many spectrum auctions worldwide. Since its inception, the CCA has been in almost continual evolution. We begin by reviewing some important changes which have already occurred. Despite these enhancements, we observe that the performance of the CCA is still limited by weak activity rules, suboptimal price feedback, and a missing-bid problem. We then describe further evolutionary changes, including new activity rules, new approaches to pricing, and an integration of non-mutually-exclusive bids, which will help to address these issues.

We provide conditions under which contingent claim and asset demands are consistent with state independent Expected Utility maximization. The paper focuses on the case of a single commodity and demands are allowed to be functions of probabilities and not just prices and income. We extend prior analyses by deriving three distinct tests for demands to be rationalized by Expected Utility: (i) a contingent claim analogue to the certainty strong axiom of revealed preference, (ii) a characterization of the functional form for demand, and (iii) necessary and sufficient conditions based on the Slutsky matrix.

Massive Online Open Courses (MOOCs) present the potential to deliver high quality education to a large number of students. But they suffer from low completion rates. This paper identifies disorganization as a factor behind failure to complete a MOOC. Students who enroll one day late are 17 percentage points less likely to earn a certificate than students who enroll exactly on time. This reflects selection, but it does seem to be related to demographic characteristics, motivation to complete the course, or ability. This suggests that building in even more structure in the MOOC could be a factor in improving performance.

Our recent research (Budish, Cramton, and Shim 2013) proposes frequent batch auctions - uniform-price sealed-bid double auctions conducted at frequent but discrete time intervals - as a market design alternative to continuous-time trading in financial markets. This short paper discusses the implementation details of frequent batch auctions. We outline the process flow for frequent batch auctions, discuss a modification to the market design that accommodates market fragmentation and Reg NMS, and discuss the engineering and economic considerations relevant for determining the batch interval. Open questions are discussed throughout.

We document that successive cohorts of college and post-college degree graduates experienced an increase in the probability of obtaining cognitive jobs both at the start of their careers and with time in the labor market in the 1990s. However, this pattern reversed for cohorts entering after 2000; profiles of the proportion of a cohort in cognitive occupations since school completion fall and become flatter with successive cohorts. Since cohort-wage profiles display a similar pattern, these findings appear to fit with a strong increase in demand for cognitive tasks in the 1990s followed by a decline in the 2000s.

We look at the effects of rainfall forecasts and realized rainfall on equilibrium agricultural wages over the course of the agricultural production cycle. We show theoretically that a forecast of good weather can lower wages in the planting stage, by lowering ex ante out-migration, and can exacerbate the negative impact of adverse weather on harvest-stage wages. Using Indian household panel data describing early-season migration and district-level planting- and harvest-stage wages over the period 2005-2010, we find results consistent with the model, indicating that rainfall forecasts improve labor allocations on average but exacerbate wage volatility because they are imperfect.

We show that, among college graduates, earnings differentials across field of study have increased substantially since the early 1990s. We study the degree to which this increase can be accounted for by changes in the labor market return to skills associated with a major. To do so, we define major-specific measures of the relative importance of abstract, routine, and manual tasks on the job, by linking majors to the occupations they typically lead to. Changes in the relationship between earnings and these measures can account for about two-thirds of the rise in inequality.

Short-term collateralized debt, private money, is efficient if agents are willing to lend without producing costly information about the collateral backing the debt. When the economy relies on such informationally insensitive debt, firms with low quality collateral can borrow, generating a credit boom and an increase in output. Financial fragility is endogenous; it builds up over time as information about counterparties decays. A crisis occurs when a ( possibly small) shock causes agents to suddenly have incentives to produce information, leading to a decline in output. A social planner would produce more information than private agents but would not always want to eliminate fragility.