Knowledge that Transforms

The Nigerian civil war of 1967-70 was precipitated by secession of the Igbo-dominated south-eastern region to create the state of Biafra. It was the first civil war in Africa, the predecessor of many. We investigate the legacies of this war four decades later. Using variation across ethnicity and cohort, we identify significant long-run impacts on human health capital. Individuals exposed to the war at all ages between birth and adolescence exhibit reduced adult stature and these impacts are largest in adolescence. Adult stature is portentous of reduced life expectancy and lower earnings.

We document that the percentage of all U.S. assets that are “safe” has remained stable at about 33 percent since 1952. This stable ratio is a rare example of calm in a rapidly changing financial world. Over the same time period, the ratio of U.S. assets to GDP has increased by a factor of 2.5, and the main supplier of safe financial debt has shifted from commercial banks to the “shadow banking system.” We analyze this pattern of stylized facts and offer some tentative conclusions about the composition of the safe-asset share and its role within the overall economy.

Our paper examines whether the failure of unsophisticated investors to rebalance their portfolios can help to explain the countercyclical volatility of aggregate risk compensation in financial markets. To answer this question, we set up a model in which a large mass of investors do not rebalance their portfolio shares in response to aggregate shocks, while a smaller mass of active investors do. We find that intermittent rebalancers more than double the effect of aggregate shocks on the time variation in risk premia by forcing active traders to sell more shares in good times and buy more shares in bad times. (JEL D14, E32, G11, G12)

We characterize the design of an optimal trade agreement when governments are privately informed about the value of tariff revenue. We show that the problem of designing an optimal trade agreement in this setting can be represented as an optimal delegation problem when a money burning instrument is available. In a specification with quadratic payoffs and a uniform distribution, we find that the tariff cap and the probability of binding overhang are higher when the upper bound of the support distribution is higher and when the support distribution has greater width.

US productivity growth accelerated after 1995 (unlike Europe's), particularly in sectors that intensively use information technologies (IT). Using two new micro panel datasets we show that US multinationals operating in Europe also experienced a “productivity miracle.” US multinationals obtained higher productivity from IT than non-US multinationals, particularly in the same sectors responsible for the US productivity acceleration. Furthermore, establishments taken over by US multinationals (but not by non-US multinationals) increased the productivity of their IT. Combining pan-European firm-level IT data with our management practices survey, we find that the US IT related productivity advantage is primarily due to its tougher “people management” practices. (JEL D24, E23, F23, M10, M16, O30)

Why did Finland experience, in 1991–1993, the deepest recession observed in an industrialized country since the 1930s? Using a dynamic general equilibrium model with labor frictions, we argue that the collapse of the Soviet-Finnish trade was a major contributor to the contraction. Finland's experience mirrors that of the transition economies of Eastern Europe, which suffered similar deep recessions coupled with institutional changes. By focusing on the Finnish case, we isolate the effects of the Finnish-Soviet trade collapse and shed new light on the sources of recessions in transition economies.

For a mechanism designer with an objective such as welfare we propose a method for robustly ranking mechanisms. The method is based on eliminating weakly dominated strategies only, and thus does not require any assumptions about agents' beliefs about each other except full support. We illustrate the usefulness of this method in two examples: bilateral trading and voting. In both examples we show that there are mechanisms that are ranked by our method above dominant strategy mechanisms. These examples question the literature's focus on dominant strategy mechanisms in cases when such mechanisms yield undesirable outcomes.

We examine the impact of the 2002-07 civil conflict in Cote d'Ivoire on children's health status measured by height-for-age. We use pre- and post-war survey data coupled with information on the location of violent incidents to capture exposure to the conflict of children born during 1997-2007. Our results indicate that children from regions more affected by the conflict suffered significant health setbacks compared with children from less affected regions. Further, household-level victimization -- such as war-related economic stress, health stress, and displacement -- has a large and negative effect on child health in conflict-affected regions.

Hires occur for two reasons - to grow a business and to replace those who have left (churn). Churn is an important part of employment dynamics, allowing workers to move to their most productive use. We present evidence on churn from the Job Openings and Labor Turnover Survey (JOLTS). Churn is procyclical. During the 2007-09 recession, four-fifths of hiring reductions are associated with reduced churn, not with reductions in job creation. We estimate that the cost of reduced churn is about two-fifths of a percentage point of GDP annually throughout the three-and-one-half year period since the beginning of the recession.

We propose a new strategy for a pervasive problem in the hedonics literature: recovering hedonic prices in the presence of time-varying correlated unobservables. Our approach relies on an assumption about home buyer rationality, under which prior sales prices can be used to control for time-varying unobservable attributes of the house or neighborhood. Using housing transactions data from California's Bay Area between 1990 and 2006, we apply our estimator to recover marginal willingness to pay for reductions in three of the EPA's “criteria” air pollutants. Our findings suggest that ignoring bias from time-varying correlated unobservables considerably understates the benefits of a pollution reduction policy. (JEL D12, D84, Q53, Q58, R21)