MATERIAL REQUIREMENTS PLANNING UNDER UNCERTAINTY

This paper presents a framework for characterizing and studying the uncertainty which can affect inventory investment and service level performance in a material requirements planning (MRP) system. It also presents the results of a simulation experiment which compared two techniques (safety stock and safety lead time) for building inventory to protect against uncertainty. The simulation results disclose consistent differences between the techniques in protecting a representative part against timing and quantity uncertainty in both demand and supply for the part. The paper not only provides some initial insights into the behavior of MRP systems under uncertainty, but also establishes some guidelines for choosing between safety stock and safety lead time.     

PERFORMANCE OF THE EXPECTED UTILITY METHOD AND TWO OTHER NORMATIVE METHODS IN INSURANCE DECISION MAKING*

In an experiment, thirty-six professional insurance men employed the utility method, the worry method, and the comparison method in two insurance problems to determine the appropriate insurance coverage. It was found that the best act with the utility method almost always was no insurance, whereas the best act with the other two methods tended to be complete insurance. The utility method best act rarely agreed with the subject's actual preferred act, while the comparison method best act usually was the same or almost the same as the actual preferred act. While the worry method suggests that the subjects typically are risk averse, the utility functions obtained tend to show that the subjects typically are not risk averse.     

A METHOD FOR SOLVING LINEAR PROGRAMS WITH VARIABLE RESOURCES

This paper is concerned with the solution of linear and linear goal programming problems in which the values of the right-hand side parameters are not fixed constants. Specifically, we are concerned with linear optimization problems in which the right-hand sides of the constraining equations are free to vary subject to a set of linear constraining equations. By formulating a relaxed linear program wherein the right-hand sides are treated as variables, we show how it is possible to solve one larger linear program that yields as a solution not only the optimal values for the decision variables, but also the optimal values for the right-hand sides.     

Human capital and agency effects on CEO compensation of IPO biopharmaceutical firms and the market’s response

This paper examines the determinants of base pay and total incentive compensation packages of CEOs of biopharmaceutical firms that have recently gone public, and whether human capital and agency factors affect the market’s response to the initial public offering. We find that in terms of net proceeds, the IPO market appears to reward the firms that have founder-CEOs and CEOs with higher incentive compensation. CEOs with prior venture capital experience are associated with receiving higher incentive compensation, while CEOs with a greater ownership interest in the firm receive lower incentive compensation but higher salaries. CEOs of firms with a greater percentage of insiders are associated with lower salaries. The results should add to our understanding related to human capital and agency theories, as well as help firms and investors better understand and structure CEO compensation.     

From violence to alliance: Maroons and white settlers in Jamaica, 1739–1795

During the First Maroon War, violent battles between Maroons and British colonists were frequent and violent. How then, after the peace treaties, did former enemies negotiate their new positions as allies? How did colonists accept this new status quo while balancing it with racial beliefs of the era? This article examines Maroon and colonist efforts to progress in a physically difficult and socially charged environment while living side-by-side with a large enslaved population. Ultimately, some influential planters, as opposed to poorer settlers, came to recognise the mutual benefits this uneasy peace provided. That is not to say these colonists were not fearful of the Maroons but that they recognised the usefulness of the Maroon communities.     

Study-work satisfaction and psychological distress in older university students

In order to study the relationships between work satisfaction and mental health in a group known to be at risk for psychological distress, university students who were somewhat older than usual (n=568, average age 24 years) provided infomiation by questionnaire about their satisfactions from study and paid work, and their level of psychological distress. The measure of study satisfaction was a modified form of Warr et al.'s (1979) Job Satisfaction Scale, and had good reliability. Study satisfaction waslower for undergraduate than for postgraduate students, due to lack of clearly defined identity, less supportive relations with fellow-students and teaching staff, and financial hardship. For all subjects the availability of teacher support predicted study satisfaction, and study satisfaction had a major influence on the students' psychologcal well-being.     

A Weibull Regression Model with Gamma Frailties for Multivariate Survival Data

Frequently in the analysis of survival data, survival times within the same group are correlated due to unobserved co-variates. One way these co-variates can be included in the model is as frailties. These frailty random block effects generate dependency between the survival times of the individuals which are conditionally independent given the frailty. Using a conditional proportional hazards model, in conjunction with the frailty, a whole new family of models is introduced. By considering a gamma frailty model, often the issue is to find an appropriate model for the baseline hazard function. In this paper a flexible baseline hazard model based on a correlated prior process is proposed and is compared with a standard Weibull model. Several model diagnostics methods are developed and model comparison is made using recently developed Bayesian model selection criteria. The above methodologies are applied to the McGilchrist and Aisbett (1991) kidney infection data and the analysis is performed using Markov Chain Monte Carlo methods. This revised version was published online in July 2006 with corrections to the Cover Date.