The optimal portfolio for the two-pillar mandatory pension system: the case of Poland

In the recent decade, there has been observed across the Central and Eastern European states the regulatory trend towards the increase of the non-financial (first) pension pillar size at the expense of the financial (second) pillar. It tends to question the consequences of this shift for the future retirement benefits. Applying the portfolio approach we address this issue by running a series of simulations to find out how to allocate pension contributions between both pillars in an optimal way. Our study contributes to the existing literature as follows. First, we do not perform the assessment of the predetermined regulatory solutions, but we look for an optimal one. Moreover, we allow our optimal rule to be time-varying, if necessary, which would be a true novelty in this research area. Second, we do not base our estimates on historical trends; rather, we apply the long-term economy’s projection to account for the society’s ageing impact, which is a crucially important factor for the solvency of the pension system. Adapting some of the simulation assumptions to fit the Polish case, our results confirm that current regulations underestimate the role of the capital pillar and the optimal allocation between both pillars should be time-varying.     

Consistency and optimality in a dynamic game of pollution control II: Monopoly

This paper continues a line of research begun in Batabyal (1995a). I model the interaction between a regulator and a monopolistic, polluting firm as a Stackelberg differential game in which the regulator leads. The firm creates pollution, which results in a stock externality. I analyze the intertemporal effects of alternate pollution control measures. The principal issue here concerns the dynamic inconsistency of the optimal solution. Inter alia, I compare the steady state levels of pollution under optimal and under dynamically consistent policies.     

Take a risk: Preferring prevention over control of biological invaders

Scientists have argued that invasive species can be managed most cost effectively with greater investments in prevention. Further, under ideas like the precautionary principle it is reasonable to expect that a cautious manager would use more prevention relative to control because it keeps more invaders out. Yet, this is not typically done. In many cases, private and public resources are invested primarily to control existing invaders rather than to prevent new invasions. Managers frequently wait until after invaders have arrived and then scramble to limit the damages. We believe these paradoxical decisions can be understood by recognizing the link between typical human preferences for risk bearing and the technology of risk reduction. We demonstrate quantitatively how managers perceived to be cautious or averse to risk tend to shy away from prevention relative to control. This counterintuitive result arises because control is a safer choice than prevention because its productivity is relatively less risky: it works to remove existing invaders from the system. In contrast, the productivity of prevention is more uncertain because prevention only reduces the chance of invasion, it does not eliminate it, and invasion may not occur even in the absence of prevention. Managers' averse to risk will inherently avoid as much uncertainty as possible, whether the source of uncertainty regards ecological outcomes or economic productivity. Implications for environmental decision making are clear. In invasive species management, if managers act as though they are risk averse, their caution can backfire when it leads to more control rather than prevention. The social consequences of this choice are a greater probability of future invasions and lower social welfare. Our results suggest that social welfare is highest when managers were willing to “take a risk” with prevention.     

城市商圈布局的三维动态模型构建与述评

商贸产业是维系一个城市经济运转的原动力之一,城市商圈是这个经济发展动力的重要载体.本文在吸收西方经典商圈理论模型的基础上,结合我国城市商圈发展现状,从外部环境、内部成长和时间三个维度分析其影响因素,构建了城市商圈布局的三维动态模型,以期对城市商圈布局和城市经营提供一定的现实参考价值.     

基于随机动态规划法的IT项目经济评价

传统的项目经济评价方法--TOC和ROI法不能有效地分析IT项目的投资价值,还可能导致错误的投资决策.通过引入随机动态规划法,可导出两类IT项目(购置型项目和自主开发项目)的经济评价模型,给出项目的投资决策临界值解,并进行详细的影响因素敏感性分析.该评价模型放松了金融期权定价模型的假设前提,更符合IT项目的实际情况,从而能准确地评估IT项目中内含的期权价值和投资机会价值.     

固定资产动态折旧的分类模型与通用模型构建

文章参照固定资产静态折旧的几种典型模型,构建了直线动态折旧模型、折旧基数变化情况下的加速动态折旧模型、折旧率变化情况下的加速动态折旧模型,分别根据各种折旧模型各自折旧额的内在规律性进行建模,比较好地实现了从静态折旧模型向动态折旧模型的转化.在此基础上,本文试图去寻找各种动态折旧模型中各期折旧额的共同规律,进而建立起固定资产动态折旧的通用模型,以供企业根据自己的实际情况代入相应初始条件直接套用固定资产动态折旧的通用模型,方便地计算固定资产各期的动态折旧金额.     

物流市场供需的动态弹性分析

运用系统动力学的思想,通过对物流市场特点的分析,借助于动态弹性分析手段建立了物流市场供需的动态弹性模型。根据模型的结果模拟出了物流市场的供需趋势图,并借助于一个实例进行了具体运用,较准确的预测出物流市场的供需趋势,为决策提供了很好的支持。     

软件限时开发方法的研究与应用

限时开发是快速应用开发的最佳实践之一。文章介绍了限时开发的基本概念和优点以及适用的项目范围,通过一个进销存软件的开发实例说明如何成功地应用限时开发方法。     

The Dynamics of Capital Structure in Transition Economies

This paper uses a dynamic unrestricted capital structure model to examine the determinants of the private companies' target financial leverage and the speed of adjustment to it in two transition economies, the Czech Republic and Bulgaria. We explicitly model the adjustment of companies' leverage to a target leverage, and this target leverage is itself explained by a set of factors. The panel data methodology combines cross-section and time-series information. The results indicate that the Bulgarian corporate credit markets were less supply -constrained than those of the Czech Republic during the period under investigation. Bulgariancompanies adjusted much faster to the target leverage than Czech firms. The speed ofadjustment related positively to the distance between target and observed ratio for Bulgarian companies while the relationship was neutral for Czech companies. The conservative policies of Czech banks and the exposure control were likely responsible for the slower adjustment among the larger companies while the opposite were true for Bulgarian banks and companies.     

虚拟物流--第三方物流企业未来发展方向

虚拟物流是第三方物流企业的未来发展方向.本文介绍了我国第三方物流企业的现状、论述了虚拟物流的概念、分析了我国第三方物流采取虚拟经营的优势.