Medical innovation and its diffusion: Implications for economic performance and welfare

We study the impact on economic performance and welfare of medical innovations and their endogenous diffusion. We construct a general equilibrium model with a medical sector and overlapping generations subject to endogenous mortality and calibrate it to reflect the development of the US economy and health care over the cardiac revolution during the 1980s and 1990s. By counterfactual analysis we find that (i) medical innovations have increased welfare without compromising GDP growth; (ii) there is a sizeable welfare loss due to the adoption lag involved with imperfect diffusion; and (iii) there is scope for Pareto improvement by way of subsidization of innovative health care.     

Structural Changes in the Labor Market and the Rise of Early Retirement in France and Germany

The rise of early retirement in Europe is typically attributed to the European system of taxes and transfers. A model with an imperfectly competitive labor market allows us to consider also the effects of bargaining power and of matching efficiency on pre‐retirement. We find that lower bargaining power of workers and declining matching efficiency have been important determinants of early retirement in France and Germany. These structural changes, combined with early retirement transfers and population aging, are also consistent with the employment and unemployment rates, labor share and seniority premia.     

美国行政法上的机构协调及其借鉴

机构协调是美国行政法处理行政管辖碎片化、重叠化问题,增强行政效能的重要内部行政法举措。美国机构协调的制度体系主要包括国会和总统对机构协调的外部控制措施,行政机构自主开展的协调规则制定和协调裁决等要素。非正式协调、信息科技等对美国机构协调也具有重要影响。除遵守普通行政程序外,美国机构协调还在意见咨询、行政公开和说明理由方面具有特殊的程序设计。美国机构协调的司法审查主要从四方面展开,即协调组织是否属于行政机关、机构协调是否违反“单方接触”、协调制定的行政规范是否具有效力和机构协调执法的合法性要求。借鉴美国经验,结合我国实际,宜从理论内化、规则创制、程序约束与法院审查等方面入手,建立健全我国行政法上的机构协调制度。     

公共资本投资、内生经济增长与合理政府债务规模*

本文基于一个具有内生增长机制的三部门世代交叠模型,讨论了政府举债为公共投资进行融资时经济的长期均衡;同时,通过数值模拟方法考察了我国的均衡政府债务规模及其影响因素。结果表明：在特定条件下,经济系统存在一个正的均衡政府债务-产出比重,该债务比重水平明显受到公共投资—产出比重、公共投资的债务融资比重、民间资本产出弹性等参数的影响。但是,均衡政府债务比重并不是无限上升的,当上述参数超过特定临界值时,经济系统无法达到均衡,政府债务-产出之比将持续上升,财政将不可持续。另外,当民间资本产出弹性较低时,较高的均衡政府债务比重可能导致经济运行动态无效率。数值模拟结果还显示,基于不同的假设情形,我国的均衡政府债务-产出比重均在不同程度上高于当前实际的政府债务规模,这为我国在未来期间实施扩张性财政政策提供了有利的依据。     

论降低缴费率对养老金给付的影响——基于现收现付制度的视角

在现收现付制中,当前养老金缴费的减少对养老金的给付不一定有消极的影响。由于养老金的给付水平取决于资本份额的分配和跨主观贴现因子,利用简化的戴蒙德的叠代模型证明,当生产资本权重较高和主观贴现因子较低时,当前年轻一代缴费率的减少会提高养老金的给付水平。     

动态无效率产生的原因解析——对David Romer《高级宏观经济学》教科书观点的修正

美国经济学家David Romer通过一个特例说明有可能存在动态无效率的现象,而没有深究为什么会存在这种现象,这种做法在美国高级宏观经济学教科书中一脉相承。通过对拉姆齐模型和世代交叠模型的比较,本研究发现,动态无效率的现象源于世代交叠模型两期寿命的假定,导致实际利率的变化缺少了约束,会低于持平投资的增长率。本研究指出:动态无效率不是来源于资本动态学方程的特例,而是来源于模型的期限结构,内生于模型的结构。萨缪尔森世代交叠模型可以证明本研究的结论。     

The Modeling Process for Stage Models

The purpose of this paper is to present and test a modeling procedure because researchers have struggled for decades to develop stages-of-growth models that are both theoretically founded and empirically validated. This article presents the concept and hypothesis of stages, the history of stage models, and a procedure that may serve as a useful tool in modeling stages of growth. Based on previous research and lessons learned from case study experience of the government sector in Norway, a procedure for the stages of growth modeling process is suggested and demonstrated. The procedure is used for developing a stage model for e-government interoperability. This article provides new insight into issues and challenges faced when engaging in stages of growth research. The paper proposes a new approach to stages of growth modeling. The utility of the suggested procedure is to improve theory building and empirical validation. The contribution to academia is the modeling process that can be applied in future developments of stages of growth. The contribution to practice lies in the stage hypothesis of organizational development over time.     

The predictive accuracy of credit ratings: Measurement and statistical inference

Credit ratings are ordinal predictions of the default risk of an obligor. The most commonly used measure for evaluating their predictive accuracy is the Accuracy Ratio, or equivalently, the area under the ROC curve. The disadvantages of these measures are that they treat default as a binary variable, thus neglecting the timing of default events, and they fail to use all of the information available from censored observations. We present an alternative measure which is related to the Accuracy Ratio but does not suffer from these drawbacks. As a second contribution, we study statistical inference for the Accuracy Ratio and the proposed measure in the case of multiple cohorts of obligors with overlapping lifetimes. We derive methods which use more sample information and lead to tests which are more powerful than alternatives which filter just the independent part of the dataset. All procedures are illustrated in the empirical section using a dataset of S&P Credit Ratings.     

Climate Change and the Representative Agent

The artifice of an infinitely-lived representative agent iscommonly invoked to balance the present costs and future benefitsof climate stabilization policies. Since actual economies arepopulated by overlapping generations of finite-lived persons,this approach begs important questions of welfare aggregation.This paper compares the results of representative agent andoverlapping generations models that are numerically calibratedbased on standard assumptions regarding climate--economyinteractions. Under two social choice rules -- Pareto efficiencyand classical utilitarianism -- the models generate closelysimilar simulation results. In the absence of policies toredistribute income between present and future generations,efficient rates of carbon dioxide emissions abatement rise from15 to 20% between the years 2000 and 2105. Under classicalutilitarianism, in contrast, optimal control rates rise from 48 to 79% this same period.     

解释经济波动现象的两种理论比较

真实经济周期理论从微观出发研究宏观经济,认为经济周期的产生原因来自于经济体系之外的真实冲击,其对宏观经济波动的解释与传统凯恩斯主义波动理论观点迥异,从而对后者在宏观经济研究中的统治地位提出了挑战,并为经济研究开拓了新的思路。比较了两种理论在经济波动的原因、性质、传播机制、研究方法、模型以及政策含义等方面的差异,并评价了两种理论各自的优劣之处。