We report a puzzling pair of facts concerning the organization of science. The concentration of research output is declining at the department level but increasing at the individual level. For example, in evolutionary biology, over the period 1980 to 2000, the fraction of citation-weighted...

This study presents the first evidence on the relation of consumption to lifetime wealth, based on data from the 1973 and 1975 Retirement History Survey that have been linked to Social Security earnings records. Nearly 500 white, married, fully retired couples ages 62-69 form the basis of the...

Cigarette smoking leads to large healthcare and morbidity costs, and mortality losses, and smoking cessation plays a key role in reducing health risk and economic costs. While medical evidence suggests that some smokers are more likely to respond to medication treatment than others depending on...

Aggregate citation behavior plays a key role in scientific knowledge diffusion, as citations document the collective and cumulative nature of knowledge production. Additionally, citations are commonly taken as input for several influential evaluative metrics used to assess researchers'...

This paper derives optimal income tax and human capital policies in a dynamic life cycle model of labor supply and risky human capital formation. The wage is a function of both stochastic, persistent, and exogenous "ability'' and endogenous human capital. Human capital is acquired throughout...

This paper extends the standard life cycle model to a world in which there are also capitalists. We obtain simple formulae describing the equilibrium fraction of wealth held by life-cycle savers. Using these formulae, we ascertain the effects of tax policy or changes in the parameters of the...

This paper reports on the construction of a new dataset that combines data on trademark applications and registrations from the U.S. Patent and Trademark Office with data on firms from the U.S. Census Bureau. The resulting dataset allows tracking of various activity related to trademark use and...

Comparisons of individual life expectancies over time and across demographic groups provide information for individuals making retirement decisions and for policy makers. For couples, analogous measures are the expected years both spouses will be alive (joint life expectancy) and the expected...

This paper explores how an environment of persistent low returns influences saving, investing, and retirement behaviors, as compared to what in the past had been thought of as more “normal” financial conditions. Our calibrated lifecycle dynamic model with realistic tax, minimum distribution,...

We study the leverage of U.S. firms over their life-cycles, and the connection between firm leverage, firm growth, and aggregate shocks. We construct a new dataset that combines private and public firms' balance sheets with firm-level data from U.S. Census Bureau's Longitudinal Business Database...