[I use a new technique to derive a closed-form solution for the price of a European call option on an asset with stochastic volatility. The model allows arbitrary correlation between volatility and spot-asset returns. I introduce stochastic interest rates and show how to apply the model to bond options and foreign currency options. Simulations show that correlation between volatility and the spot asset's price is important for explaining return skewness and strike-price biases in the Black-Scholes (1973) model. The solution technique is based on characteristic functions and can be applied to other problems.]

Implied volatility is widely believed to be informationally superior to historical volatility, because it is the “market’s” forecast of future volatility. But for S&P 100 index options, the most actively traded contract in the United States, we find implied volatility to be a poor forecast of subsequent realized volatility. In aggregate and across subsamples separated by maturity and strike price, implied volatility has virtually no correlation with future volatility, and it does not incorporate the information contained in recent observed volatility.

This paper attempts to demonstrate how “diversity theory” can be applied to the analysis of real-world conservation policies. The specific example chosen to serve as a paradigm concerns preservation priorities among the fifteen species of cranes living wild throughout the world. The example is sufficiently actual to show how diversity theory can be used operationally to frame certain critical conservation questions and to guide us toward answers by providing informative quantitative indicators of what to protect. At the same time the cranes example is rich enough that it illustrates nicely some broad general principles about the economics of diversity preservation.

This paper investigates the warrant pricing abilities of dilution-adjusted versions of the Black-Scholes and Jump-Diffusion option pricing models. Because of the typically long lives of warrants, their pricing is hypothesized to benefit from use of the Jump-Diffusion model, which relaxes the Black-Scholes restriction against stock price jumps. Empirical results indicate that while the Black-Scholes model almost uniformly provides more efficient estimates, the Jump-Diffusion model generally provides less biased estimates of market value. Particularly for the valuation of out-of-the-money warrants and warrants on stocks with a history of large and/or frequent jumps, the Jump-Diffusion model may be preferred.

Abstract. The Securities and Exchange Commission requires disclosure of auditor‐client disagreements that precede a change in auditor. Although prior research has documented that disclosure of disagreements is associated with a decline in equity value, no empirical work has examined factors that result in auditor‐client disagreements. We hypothesize that managers are motivated by debt and compensation arrangements to propose methods that are objected to by their auditors (resulting in a disagreement). Because of their greater independence, we also hypothesize that reported disagreements will be more likely for Big Eight (now Big Six) auditors, A comparison of 40 firms that changed auditors and reported a disagreement with a control group of 40 firms that simply changed auditors revealed that disagreement firms are more likely to have debt covenant violations. Disagreement firms are also more likely to have higher leverage, a decline in earnings, and Big Eight auditors. For firms that disclosed the magnitude of the disagreement's effect on earnings, the use of the questionable procedure tended to enhance “flat” earnings growth. Résumé. La Securities and Exchange Commission exige que soit publiée l'information relative aux désaccords vérificateur‐client qui précèdent un changement de vérificateurs. Bien que les recherches antérieures aient démontré que la publication de cette information est accompagnée d'un déclin de la valeur des titres, aucun travail empirique n'a examiné les facteurs qui sont à l'origine des désaccords vérificateur‐client. Les auteurs posent l'hypothèse selon laquelle ce sont le passif et les régimes de rémunération qui motivent les gestionnaires à proposer des méthodes auxquelles s'opposent les vérificateurs (et qui donnent lieu à un désaccord). Les auteurs posent également l'hypothèse selon laquelle il est plus probable que les désaccords déclarés mettent en cause les huit grands cabinets d'experts‐comptables (maintenant les six grands), étant donné leur indépendance plus grande. La comparaison de 40 entreprises ayant changé de vérificateurs et fait état d'un désaccord à un groupe de contrôle de 40 entreprises ayant simplement changé de vérificateurs a révélé que les entreprises en désaccord sont davantage susceptibles d'avoir dérogé à des clauses restrictives. Les entreprises qui déclarent être en désaccord avec leurs vérificateurs sont aussi davantage susceptibles d'être caractérisées par un levier financier élevé, un déclin dans les bénéfices et le recours aux services d'un cabinet d'experts‐comptables appartenant aux huit grands. Dans le cas des entreprises qui ont fait état de l'ampleur des conséquences du désaccord sur les bénéfices, l'utilisation du procédé discutable a eu tendance à favoriser une croissance « horizontale » des bénéfices.

This article reports on an empirical analysis of the relationships between alcoholism and income and working. We show that the relationships between alcoholism and labor market success have important age or life-cycle dimensions. We present evidence that alcoholism may affect income more by restricting labor market participation than by affecting the wages of workers. Finally, we demonstrate that the effects of alcoholism on earnings depend on the extent to which one controls for other covariates associated with alcoholism; as such, we suggest that there may be important indirect as well as direct effects of alcoholism on labor market success.

Over the 1980s, there were sharp increases in the return to schooling estimated with conventional wage regressions. The authors explore whether the relationship between ability and schooling changed over this period in ways that would have increased the schooling coefficient in these regressions. Their empirical results reject the hypothesis that an increase in the bias of the schooling coefficient, due to a change in the relationship between ability and schooling, has contributed to observed increases in the return to schooling. The authors also find that the increase in the schooling return has occurred for workers with relatively high levels of academic ability. Copyright 1993 by University of Chicago Press.