POWER APPROXIMATIONS FOR A TWO-ECHELON INVENTORY SYSTEM USING SERVICE LEVELS

We consider a two-echelon inventory system with one warehouse and several stores. The warehouse as well as the stores are controlled by periodic review (s, S) inventory policies. We study the interrelationship between the safety stocks at the warehouse and the stores. Stockouts at the warehouse will result in supply delays to the stores and cause the lead time to be stochastic. The stores may react by increasing their safety stock. However, there is a trade-off between the safety stock at the warehouse and the safety stock at the stores. We use a service level at the warehouse to quantify the effect of warehouse stockouts on the lead time to the stores. The service level at the warehouse is considered a decision variable to find the best compromise between the various safety stocks by minimizing the overall costs. Using power approximations for the (s, S) policies, we provide an iterative procedure for adjusting the lead time distribution to the stores; this can result in substantial savings, but it doesn't guarantee the overall optimality. Numerical studies are provided to test the accuracy of approximations. The effects of the different system parameters on the inventory policy give general guidelines for use of the policies.     

ENVIRONMENTAL REGULATION: WHOSE SELF-INTERESTS ARE BEING PROTECTED?

Special interest can explain why environmental policy limits economic activity in areas where air quality is above minumum standards. Locational competition among region helped create a policy that raised factor mobility cost from slower to faster growing regions. Analysis of votes shows greater support for this policy was received from northern urban constituencies and the greatest opposition came from the South and the West. Pollution abatement costs per unit of output are higher in areas with higher not lower air quality.     

Work,family and the care of children: issues of equality and responsibility

SUMMARY. The current growth in women's employment, particularly among women with young children, gives new prominence to an issue of major political, economic and social importance, involving men as well as women and children: the relationship between paid work and family responsibilities and how to reconcile these demands without creating inequalities or stress for children or parents, especially mothers. The paper considers the Government's response to this development, arguing that it should be taking a strategic or leadership role, working in active partnership with employers, trades unions, local authorities, voluntary organisations and parents. Examples from Sweden, Spain and New Zealand are given to illustrate this alternative approach     

Simplex Mixed‐Effects Models for Longitudinal Proportional Data

Abstract. Continuous proportional outcomes are collected from many practical studies, where responses are confined within the unit interval (0,1). Utilizing Barndorff‐Nielsen and Jørgensen's simplex distribution, we propose a new type of generalized linear mixed‐effects model for longitudinal proportional data, where the expected value of proportion is directly modelled through a logit function of fixed and random effects. We establish statistical inference along the lines of Breslow and Clayton's penalized quasi‐likelihood (PQL) and restricted maximum likelihood (REML) in the proposed model. We derive the PQL/REML using the high‐order multivariate Laplace approximation, which gives satisfactory estimation of the model parameters. The proposed model and inference are illustrated by simulation studies and a data example. The simulation studies conclude that the fourth order approximate PQL/REML performs satisfactorily. The data example shows that Aitchison's technique of the normal linear mixed model for logit‐transformed proportional outcomes is not robust against outliers.     

Financial Returns of Corporate Social Responsibility,and the Moral Freedom and Responsibility of Business Leaders

A number of theorists have proposed mechanisms suggesting that corporate social responsibility produces better financial results. Others subscribe to the theory that, realistically, less ethical means are necessary. This article contains an analysis of these perspectives drawing on observations from evolutionary game theory and nature. Based on these analyses, it is concluded that the financial returns of corporate social responsibility and irresponsibility (CSR and CSI) are equal on average. The explanation is that CSR and CSI aredriven to a state of equilibrium, because if one or the other were to offer higher profits, it would attract more players who would compete for the best opportunities until there was no difference in average profit. Existing empirical research generally shows a positive correlation between CSR as measured and corporate financial performance. It is argued that what is actually causing that finding is probably not CSR but management skill. More skillful managers, whether actually responsible or irresponsible, are able to obtain both higher profits and greater credit in imperfect measures of CSR. Next it is shown that this theory of equal returns implies greater moral freedom and therefore responsibility for business leaders. It is concluded that this insight can intensify the interest of decent business leaders in vigorously championing CSR.     

MANUFACTURING PROCESS TECHNOLOGY and SUPPORT STAFF COMPOSITION: AN EMPIRICAL VIEW OF INDUSTRY EVIDENCE

Despite the attention given to restructuring and trimming down manufacturing firms during the 198Os, little attention has been paid to the mix of skills they needed under different circumstances. We examined the patterns of employment by occupation in manufacturing industries utilizing different production technologies and the effect of establishment size on nonproduction employment. We found that a relationship exists between production technology and nonproduction employment per 100 production workers. Establishment size is found to be a moderator between nonproduction employment and production technology. Our findings imply two clear messages for managers. First, when considering major changes in production technology, managers should be aware that the supporting skills they will need from their nonproduction work force are likely to change greatly. Further, these changes involve technical and managerial workers as well as clerical and production support people. Second, they should restructure the functional or occupational mix of an organization in the context of the process technologies in place. Different process technologies require different structures.