How does the sustainable level of consumption depend on productivity growth and the size and growth rate of the population? What is the effect of uncertainty over these growth rates? I address these questions using a model in which productivity and population growth are stochastic, and social...

A simple model of equity pricing is developed to address two related questions. First, to what extent can unanticipated changes in such"fundamental" variables as profitability, real interest rates, inflation, and the variance of returns account for the observed behavior of the stockmarket?...

Most explanations for the decline in share values over the past two decades have focused on the concurrent increase in inflation.This paper considers an alternative explanation: a substantial increase in the riskiness of capital investments. We show that the variance of firms' real gross...

There is a lot we know about climate change, but there is also a lot we don't know. Even if we knew how much CO2 will be emitted over the coming decades, we wouldn't know how much temperatures will rise as a result. And even if we could predict the extent of warming that will occur, we can say...

I use a simple SIR model, augmented to include deaths, to elucidate how pandemic progression is affected by the control of contagion, and examine the key trade-offs that underlie policy design. I illustrate how the cost of reducing the "reproduction number" R0 depends on how it changes the...

Any economic analysis of climate change policy requires some model that describes the impact of warming on future GDP and consumption. Most integrated assessment models (IAMs) relate temperature to the level of real GDP and consumption, but there are theoretical and empirical reasons to expect...

Focusing on tail effects, I incorporate distributions for temperature change and its economic impact in an analysis of climate change policy. I estimate the fraction of consumption w*(tau) that society would be willing to sacrifice to ensure that any increase in temperature at a future point is...

In merger analysis and other antitrust settings, risk is often cited as a potential barrier to entry. But there is little consensus as to the kinds of risk that matter - systematic versus non-systematic and industry-wide versus firm-specific - and the mechanisms through which they affect entry....

I discuss the antitrust suit brought by the U.S. Department of Justice against Visa and MasterCard in 1998. Banks that issue Visa cards are free to also issue MasterCard cards, and vice versa, and many banks issue the cards of both networks. However, both Visa and MasterCard had rules...