In recent articles, I have argued that integrated assessment models (IAMs) have flaws that make them close to useless as tools for policy analysis. IAM-based analyses of climate policy create a perception of knowledge and precision that is illusory, and can fool policy-makers into thinking that...

We show that comovements of individual stock prices cannot be justified by economic fundamentals. This finding is a rejection of the present value model of security valuation. Unlike other tests of this model, ours is robust in that it allows for volatility in ex ante rates of return. The only...

A model of capacity choice and utilization is developed consistent with value maximization when investment is irreversible and future demand is uncertain. Investment requires the full value of a marginal unit of capacity to be at least as large as its full cost. The former includes the value of...

We examine the role of consumption externalities in the demand for pharmaceuticals at both the brand level and over a therapeutic class of drugs. These effects emerge when use of a drug by others affects its value, and/or conveys information abut efficacy and safety to patients and physicians....

How likely is a catastrophic event that would substantially reduce the capital stock, GDP and wealth? How much should society be willing to pay to reduce the probability or impact of a catastrophe? We answer these questions and provide a framework for policy analysis using a general equilibrium...

The price of crude oil in the U.S. never exceeded $40 per barrel until mid-2004. By 2006 it reached $70, and in July 2008 it peaked at $145. By late 2008 it had plummeted to about $30 before increasing to $110 in 2011. Are speculators at least partly to blame for these sharp price changes? We...

In a world of certainty, the design of environmental policy is relatively straightforward, and boils down to maximizing the present value of the flow of social benefits minus costs. But the real world is one of considerable uncertainty -- over the physical and ecological impact of pollution,...

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?...

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...

This paper examines the implications of the learning curve in a world of uncertainty. We consider a competitive firm whose costs decline with cumulative output. Because the price of the firm's output evolves stochastically, future production and cumulative output are unknown, and are contingent...