A Perpetual Race to Stay Ahead

This paper presents a model of dynamic competition between two firms that repeatedly engage in an innovative activity. The state of competition—measured by the difference between the number of innovations introduced by the firms—evolves stochastically according to their effort level. The structure of Markov perfect equilibria is identified. It is generally not true that competition is fiercest when firms are closest. Rather, firms invest under two distinct circumstances: while sufficiently ahead, to outstrip their rival and secure a durable leadership; while behind, to regain leadership and prevent the situation from worsening to the point where their rival outstrips them.     

The LeChatelier-Samuelson principle revisited

Within the context of a linear Leontief model, the LeChatelier-Samuelson principle examines the effects of an increase in some final demand on the output levels under the constraint that the production of certain goods is held at its original value. The principle states that the increase in any output is larger when fewer output levels are kept constant. The present paper discusses bounds for such incremental changes, second-order effects, the consequences on the markets for the products with restricted output levels, and generalizations of the original assumptions.I would like to thank two anonymous referees for their helpful comments.     

On invariant parametric covariance families

Summary In this note we characterize all linear transformations of random vectors which are invariant for a given parametric covariance family. Two one-dimensional covariance families are discussed in detail.     

Protection for sale with imperfect rent capturing

Abstract .  Grossman and Helpman (1994) explain tariffs as the outcome of a lobbying process. In most empirical implementations of this framework protection is instead measured using non-tariff barriers. Since tariffs allow the government to fully capture the rents from protection, while non-tariff barriers do not, the existing parameter estimates of the protection for sale model are likely to be biased. To address this problem, we augment the framework by considering instruments that allow partial capturing. Our specification is supported by the data, where we find that only 72–75% of the rent from protection is appropriated by the government.