Modelling the tradeoff between postponement capacity and forecast accuracy

The ability to offer rapid delivery of a wide variety of customised products requires companies to maintain high levels of product inventories to quickly respond to customer demands. One alternative for reducing final product inventories while providing the required customer service level is delayed product differentiation, known as postponement. This strategy, however, can result in significant costs of increasing capacity at the postponement stage. Another alternative is to improve forecast accuracy, resulting in costs associated with more sophisticated forecasting methodologies. In this study we model the costs associated with each alternative and the resulting reductions in inventory levels, while maintaining a constant service level. We illustrate the interaction between these variables using a numerical example motivated by our work with a local manufacturer of non-durable household goods. Our findings show that large cost differences can exist between the two strategies, and that these costs play a significant role in determining the best strategy. Also, the value of the product (through holding cost) sets a limit on the benefit that can be realised by either strategy. These results have important managerial implications that should be considered when making the postponement decision.     

On the relationship between Spearman's rho and Kendall's tau for pairs of continuous random variables

It has long been known that for many joint distributions exhibiting weak dependence, the sample value of Spearman's rho is about 50% larger than the sample value of Kendall's tau. We explain this behavior by showing that for the population analogs of these statistics, the ratio of rho to tau approaches 3/2$3/2$ as the joint distribution approaches that of two independent random variables. We also find sufficient conditions for determining the direction of the inequality between three times tau and twice rho when the underlying joint distribution is absolutely continuous.     

Measuring longevity achievements under welfare interdependencies: a case for joint life expectancy indicators

Whereas period life expectancy constitutes an intuitive indicator of the survival conditions prevailing at a particular period, this paper argues that, given the existence of welfare interdependencies, that widespread indicator is nonetheless an incomplete measure of the longevity achievements relevant for human well-being. The central importance of coexistence for human-beings implies that usual life expectancy measures should be complemented by joint life expectancy indicators, which measure the average coexistence time under particular survival conditions. After a study of the theoretical foundations of ‘single’ and ‘joint’ life expectancy indicators, it is shown that joint life expectancy measures tend to enrich significantly the comparison of longevity achievements across countries and periods. Moreover, the introduction of joint life expectancy indicators—as a complement to conventional life expectancy measures—into multi-variable indexes such as the United Nations’ HDI is also shown to affect international rankings of standards of living to a non negligible extent.

An Investigation of Measures of Modern and Old-Fashioned Sexism

Working from the Principle of Beneficence we make the case that there is a need for adequate measures of sexism in men and women. Swim, Aikin, Hall and Hunter (1995) suggest that modern sexism represents a constellation of beliefs in which individuals: (a) disavow women's present-day discrimination; (b) reject women's demands for political and economic power; and (c) disapprove of policies designed to promote gender equality. To assess this construct, Swim et al. (1995) developed the Modern Sexism Scale (MSS), and to date, few studies have assessed its reliability and factor structure. Using data from 187 Canadian participants, confirmatory factor analysis was used to assess the unidimensionality of the MSS and Swim and associates' (1995) Old-Fashioned Sexism Scale (OFSS). Results do not support Swim et al.'s conceptualization of modern sexism as a unidimensional construct; however, the OFSS fit a unidimensional model. The implications of these findings are discussed.     

Mission Abort Policy for Systems with Observable States of Standby Components

For some critical applications, successfully accomplishing the mission or surviving the system through aborting the mission and performing a rescue procedure in the event of certain deterioration condition being satisfied are both pivotal. This has motivated considerable studies on mission abort policies (MAPs) to mitigate the risk of system loss in the past several years, especially for standby systems that use one or multiple standby sparing components to continue the mission when the online component fails, improving the mission success probability. The existing MAPs are mainly based on the number of failed online components ignoring the status of the standby components. This article makes contributions by modeling standby systems subject to MAPs that depend not only on the number of failed online components but also on the number of available standby components remaining. Further, dynamic MAPs considering another additional factor, the time elapsed from the mission beginning in the event of the mission abort decision making, are investigated. The solution methodology encompasses an event-transition based numerical algorithm for evaluating the mission success probability and system survival probability of standby systems subject to the considered MAPs. Examples are provided to demonstrate the benefit of considering the state of standby components and elapsed operation time in obtaining more flexible MAPs.     

Bandits,Militants, and Martyrs: Sub-state Violence as Claim to Authority in Late Antique North Africa

Fourth Century North Africa was a site of intense religious and political conflict. Emerging from a period of persecution and newly legitimized by the Roman state, the Christian Church immediately fractured into two competing camps. Now known as the Donatist schism, this fracture was the result of competing claims to religious authority between two camps of bishops, but the doctrinal debate at its core precipitated a specific form of violence: attacks on clergy and property perpetrated by roving groups of militant bandits. Known as circumcellions, these bands acquired a perverse reputation for religious zeal, a desire for martyrdom, and what their opponents described as the ‘madness’ and ‘insanity’ of their violence. Here I analyze sources produced by both Donatists and Catholics to trace patterns of circumcellion violence. I draw on borderland theory and research on non-state violence to argue that such acts were not mad, but rather the result of strategic efforts to consolidate religious and political power. In this, Donatism and the sectarian violence that accompanied it provide important insights into how banditry and peasant rebellions can serve as alternate sources of social and political power, avenues through which heterodox movements challenge the power state and religious hierarchies alike.     

Altruistic and Private Values For Saving Lives With an Oyster Consumption Safety Program

We use data from an Internet-based survey and estimate the benefits of an oyster consumption safety policy with the contingent valuation method. In addition to providing a context-specific estimate of willingness-to-pay for oyster safety, we consider an important issue in the contingent valuation mortality risk reduction literature. A number of studies find that willingness-to-pay for mortality risk reduction is not sensitive to the scope of the risk change. We present the scope test as a difference in the number of lives saved by the program, instead of small changes in risk, and find that referendum votes are responsive to scope. A third feature of this article is that we identify those at-risk respondents who would most benefit from the policy and decompose willingness-to-pay into use values and altruistic nonuse values. We find that willingness-to-pay per life saved ranges from $3.95 million to $7.69 million for the private good of lives saved when the respondent is at risk (i.e., use values). Willingness-to-pay per life saved including both use and altruistic nonuse values ranges from $6.89 million to $12.87 million.     

Vertical Coordination,Producer Response,and the Locus of Control over Agricultural Production Decisions1

Abstract Structural change in U.S. agriculture in part has been characterized by shifts in control over agricultural production decisions from the farm-level to off-farm firms. In the past decade, this process has accelerated as increasing concentration in production and processing has led to increased vertical integration and contract production. To retain control, some farmers have formed bargaining units, have created production and marketing networks, and have petitioned subnational state governments for regulation of production contracts. Concurrently, there has been an impressive increase in alternative marketing outlets linked with smaller-scale production based on farm-level control over production decisions. Structural change and producer collective response has a long history in U.S. agriculture. Using Mooney's and Hunt's (1996) recent contribution on recurrent ideologies of agrarian social movements, this paper outlines recent structural changes and collective responses to those changes with reference to the shifting locus of control over agricultural production decisions.