A MULTINOMIAL APPROXIMATION FOR AMERICAN OPTION PRICES IN LÉVY PROCESS MODELS

This paper gives a tree-based method for pricing American options in models where the stock price follows a general exponential Lévy process. A multinomial model for approximating the stock price process, which can be viewed as generalizing the binomial model of Cox, Ross, and Rubinstein (1979) for geometric Brownian motion, is developed. Under mild conditions, it is proved that the stock price process and the prices of American-type options on the stock, calculated from the multinomial model, converge to the corresponding prices under the continuous time Lévy process model. Explicit illustrations are given for the variance gamma model and the normal inverse Gaussian process when the option is an American put, but the procedure is applicable to a much wider class of derivatives including some path-dependent options. Our approach overcomes some practical difficulties that have previously been encountered when the Lévy process has infinite activity.     

Why Democracies Cooperate More and Fight Less: The Relationship Between International Trade and Cooperation

This paper provides an economics-based interpretation of the standard finding in the literature that democracies rarely fight each other. A general theory of conflict between two countries is presented and empirical analysis applies this theory to the question of why democracies rarely fight each other. The results show that the fundamental factor in causing bilateral cooperation is trade. Countries seek to protect wealth gained through international trade, therefore trading partners are less combative than nontrading nations. Democratic dyads trade more than nondemocratic dyads, and thus exhibit less conflict and more cooperation.     

How one hospital broke its inflation fever

The Johns Hopkins Hospital has demonstrated that hospital costs can be decreased without governmental intervention (controls). From 1975 to 1978, the hospital inflation rate was cut by half. One key factor, according to Solomon, was a move to decentralize management which was accompanied by a detailed system for monitoring costs. Also instrumental were administration's consistent reminders to physicians and managers about keeping costs down. The hospital was reorganized from a system of clinical departments that behaved, says Solomon, like "fiefdoms" into 14 autonomous departments that function under their own budgets. Each department controls about 85% of its costs (up from 30%), and is set up to function "like a small business." A breakdown of where cost reductions took place shows a savings of $5 million in overhead and $1.5 million in malpractice claims (Hopkins self-insured). Individual departments have also achieved some dramatic reductions: the Department of Medicine decreased the number of laboratory tests ordered; and the Department of Gynecology and Obstetrics built a new facility with fewer beds than the old one.