Efficiency in coalition games with externalities

A natural extension of superadditivity is not sufficient to imply that the grand coalition is efficient when externalities are present. We provide a condition, analogous to convexity, that is sufficient for the grand coalition to be efficient and show that this also implies that the (appropriately defined) core is nonempty. Moreover, we propose a mechanism which implements the most efficient partition for all coalition formation games and characterizes the resulting payoff division.     

Mean-Variance Preferences and Investor Behaviour

We study the comparative statics implications of mean-variance preferences for optimal portfolios. Specifically, we show that all risk-averse mean-variance investors raise their investment in a risky asset in response to a change in that asset's return distribution if and only if the change lowers both the mean and standard deviation of the return by the same percentage. Besides being of interest in its own right, our results allow us to compare some comparative statics implications and the expected utility and mean-variance models systematically.     

Optimal Retirement with Increasing Longevity

We develop an optimizing life‐cycle model of retirement with perfect capital markets. We show that longer healthy life expectancy usually leads to later retirement, but with an elasticity less than unity. We calibrate our model using data from the US and find that, over the last century, the effect of rising incomes, which promote early retirement, has dominated the effect of rising lifespans. Our model predicts continuing declines in the optimal retirement age, despite rising life expectancy, provided the rate of real wage growth remains as high as in the last century.     

私有化更有效率吗

本文对始自里根和撒切尔夫人主政时期的私有化浪潮提出了批评和质疑。本文认为,以解决政府失灵问题的私有化浪潮,可能导致更为严重的市场失灵问题。虽然在总体上私有企业比国有企业有更强的盈利能力,但这并不意味着私有企业比国有企业更有效率。即使能够证明私有企业比国有企业更有效率,也不能说私有化是可取的。     

A structured approach to conflict prediction in information systems strategy implementation

Organizational power and politics are the central issues of this paper. By developing a model of organizational power it is possible to determine whether an organizational change initiative is likely to be politically feasible. The formal model described has been derived largely from research reported in the social sciences. The modelling process involved using formal methods, in logic and entity relationship analysis, to discover an effective and consistent means of representing key organizational power concepts. The result is an advisory expert system called MP/L1 that can be employed by change agents to predict likely sources of potential resistance to major change initiatives and to suggest tactics that might be effective in combating anticipated resistance. Industrial experience with MP/L1 to date indicates that it has significant potential as a change management tool within the IS strategy-implementation domain. © 1998 John Wiley & Sons, Ltd.     

Nonlinear stochastic effects of substitution — an evolutionary approach

Technological innovations have been investigated by means of substitution and diffusion as well as evolution models, each of them dealing with different aspects of the innovation problem. In this paper we follow the well known research traditions on self-organisation models of complex systems. For the first time in the literature we show the existence of a specific niche effect, which may occur in the first stage of establishment of a new technology. Using a stochastic Master equation approach, we obtain analytical expressions for the survival probabilities of a new technology in smaller or larger ensembles. As a main result we demonstrate how a hyperselection situation might be removed in a stochastic picture and thresholds against the prevailing of a new technology in a step-by-step process can be overcome.     

A child health production function estimated from longitudinal data. Cebu Study Team

Collaborating researchers used a multi equation model to analyze 3080 mother-infant pairs living on the island of Cebu in the central Philippines and to estimate a child health production function. The econometric methods used eliminated obstacles such as heterogeneity and endogeneity of significant explanatory factors. They also maximized the longitudinal quality of the data. The results showed that morbidity in 1 period reduced infant weight in following periods. For example, diarrhea and febrile respiratory infection reduced growth in the time period following the illnesses. Further effects of some contributing factors were great near birth not diminished with age. For example, breast feeding promoted growth and protected against infection, especially diarrhea and febrile respiratory infection, more substantially near birth than it did later. Further, in urban areas, preventive health care positively affected growth independently of its indirect influence on reducing respiratory infection. Yet it had little effect on diarrhea. Diarrhea had a strong adverse effect on growth. Exposure of the infant to enteric pathogens had the greatest influence on production of diarrhea. In urban areas, exposure included water supply contamination, exposure to feces, a more pathogenic diet, and community crowding. In rural areas, however, exposure included community crowding and increased rainfall which presumably washed feces into the water supply. Household crowding in both urban and rural areas and irritation from smoke in urban areas only tended to bring about febrile respiratory infection.