Note on positive lower bound of capital in the stochastic growth model

In the context of the classical stochastic growth model, we provide a simple proof that the optimal capital sequence is strictly bounded away from zero whenever the initial capital is strictly positive. We assume that the utility function is bounded below and the shocks affecting output are bounded. However, the proof does not require an interval shock space, thus, admitting both discrete and continuous shocks. Further, we allow for finite marginal product at zero capital. Finally, we use our result to show that any optimal capital sequence converges globally to a unique invariant distribution, which is bounded away from zero.     

A strong incompatibility between efficiency and equity in non-convex economies

In allocation problems of perfectly divisible goods, we study the equity property of ‘no-domination', according to which no agent can receive strictly more of all goods than any other agent. We prove that no-domination is incompatible with Pareto efficiency, as soon as preferences are allowed to be non-convex.     

土地价值与城市增长

文章介绍了城市经济动态模型。通过利用在经济学中广泛的效用函数及对效用函数的优化 ,得出城市土地地租有三部份构成 :农业土地地租 ;土地发展成本的租金 ;和区位或可达性所带来的级差地租 ,并进一步推出城市土地价值有四部分构成 :(1)农业土地价值 ;(2 )土地发展成本 ;(3)可达性的经济价值 ;(4)可预见的未来土地地租增值所带来的价值。相对应 ,城市边缘非城市土地价值有两部分组成 :一是与农业土地地租有关的土地价值 ,另一个是可预见的土地转变成城市用地后未来土地地租增值所带来的价值。城市经济动态理论及其结论丰富和发展了土地地租和土地价值理论 ,加深了对土地价值形成和发展的理解 ,有利于相关法规和政策的制定 ,以此提高城市土地利用效益和推动城市发展。最后 ,结合中国国情 ,文章分析了城市政策及土地政策对城市化的社会经济影响。     

A simple urban growth model with durable housing

In the last decade the static theory of residential urban location and land use has been extensively developed. The theory has generated many useful insights, but because it ignores growth and the durability of housing and urban infrastructure there are many urban phenomena it cannot explain. In this paper a simple urban growth model with durable housing, in which all builders have perfect foresight, is presented. The discussion focuses on the qualitative differences between the economics of this model, the static class of models, and a class of dynamic models in which myopic expectations are assumed.     

A multiobjective optimization approach to smart growth in land development

In this paper we apply a multiobjective optimization model of Smart Growth to land development. The term Smart Growth is meant to describe development strategies—that do not promote urban sprawl. However, the term is somewhat open to interpretation. The multiobjective aspects arise when considering the conflicting interests of the various stakeholders involved in land development decisions: the government planner, the environmentalist, the conservationist, and the land developer. We present a formulation—employing linear and convex quadratic objective functions subject to polyhedral and binary constraints for the stakeholders. The resulting optimization problems are convex, quadratic mixed integer programs that are NP-complete. We report numerical results with this model for Montgomery County, Maryland, and present them using a geographic information system (GIS).     

多期最优资产组合选择模型分析研究

在对多期最优资产组合选择模型研究的基础上 ,着重分析了模型的求解 ,为证券投资者进行多期投资提供了科学的依据和方法。     

坚持扩大内需战略 促进经济内生增长

扩大内需是我国经济发展的根本立足点和长期战略方针,也是保持经济平稳较快发展的重大举措。对于实现＂十二五＂发展目标,加快转变经济发展方式,增强经济增长的内生动力和活力具有关键意义。本文认为,实施扩大内需战略是我国基于国内外发展形势变化做出的重大战略选择,实施扩大内需战略必须着力破解制约扩大内需的体制机制障碍,充分挖掘我国内需的巨大潜力,加快形成消费、投资、出口协调拉动经济增长的新局面。     

基于动态规划理论的工程建设企业库存管理的建模和应用

从物流活动中库存管理的视角,探讨了动态规划方法在工程项目过程中的应用。首先对我国工程建设企业库存管理的现状进行了阐述,然后对工程物流和动态规划理论等相关概念进行了介绍;最后,通过一个简单的实例详细分析了企业如何运用动态规划方法进行库存管理,使总成本最低化,获取更大的利润。     

Corruption, economic growth, and income inequality in Africa

This paper uses panel data from African countries and a dynamic panel estimator to investigate the effects of corruption on economic growth and income distribution. I find that corruption decreases economic growth directly and indirectly through decreased investment in physical capital. A unit increase in corruption reduces the growth rates of GDP and per capita income by between 0.75 and 0.9 percentage points and between 0.39 and 0.41 percentage points per year respectively. The results also indicate that increased corruption is positively correlated with income inequality. The combined effects of decreased income growth and increased inequality suggests that corruption hurts the poor more than the rich in African countries. Received: March 19, 2001 / Accepted: December 14, 2001 RID="*" ID="*" An earlier version of this paper was presented at the first AmFiTan International Conference on Development Ethics in February 2000, Dar er Salaam, Tanzania. I thank two anonymous referees of this Journal for helpful suggestions. I am, however, solely responsible for any remaining errors.     

Asset pricing with loss aversion

The use of standard preferences for asset pricing has not been very successful in matching asset price characteristics, such as the risk-free interest rate, equity premium and the Sharpe ratio, to time series data. Behavioral finance has recently proposed more realistic preferences such as those with loss aversion. Research is starting to explore the implications of behaviorally founded preferences for asset price characteristics. Encouraged by some studies of Benartzi and Thaler [1995. Myopic loss aversion and the equity premium puzzle. The Quarterly Journal of Economics 110 (1), 73–92] and Barberis et al. [2001. Prospect theory and asset prices. Quarterly Journal of Economics CXVI (1), 1–53] we study asset pricing with loss aversion in a production economy. Here, we employ a stochastic growth model and use a stochastic version of a dynamic programming method with an adaptive grid scheme to compute the above mentioned asset price characteristics of a model with loss aversion in preferences. As our results show using loss aversion we get considerably better results than one usually obtains from pure consumption-based asset pricing models including the habit formation variant.     

A comparison of monthly global indicators for forecasting growth

This paper evaluates the predictive content of a set of alternative monthly indicators of global economic activity for nowcasting and forecasting quarterly world real GDP growth using mixed-frequency models. It shows that a recently proposed indicator that covers multiple dimensions of the global economy consistently produces substantial improvements in forecasting accuracy, while other monthly measures have more mixed success. Specifically, the best-performing model yields impressive gains with MSPE reductions of up to 34% at short horizons and up to 13% at long horizons relative to an autoregressive benchmark. The global economic conditions indicator also contains valuable information for assessing the current and future state of the economy for a set of individual countries and groups of countries. This indicator is used to track the evolution of the nowcasts for the U.S., the OECD area, and the world economy during the COVID-19 pandemic and the main factors that drive the nowcasts are quantified.     

Infectious diseases and economic growth

This paper develops a framework to study the economic impact of infectious diseases by integrating epidemiological dynamics into a neo-classical growth model. There is a two way interaction between the economy and the disease: the incidence of the disease affects labor supply, and investment in health capital can affect the incidence and recuperation from the disease. Thus, both the disease incidence and the income levels are endogenous. The disease dynamics make the control problem non-convex thus usual optimal control results do not apply. We establish existence of an optimal solution, continuity of state variables, show directly that the Hamiltonian inequality holds thus establishing optimality of interior paths that satisfy necessary conditions, and of the steady states. There are multiple steady states and the local dynamics of the model are fully characterized. A disease-free steady state always exists, but it could be unstable. A disease-endemic steady state may exist, in which the optimal health expenditure can be positive or zero depending on the parameters of the model. The interaction of the disease and economic variables is non-linear and can be non-monotonic.     

The simple analytics of optimal growth with illegal migrants: A clarification

This paper reexamines the welfare effects of illegal immigration studied by Hazari and Sgro [The simple analytics of optimal growth with illegal migrants. Journal of Economic Dynamics and Control 28(1) 141–151]. In contrast to their negative conclusion, we obtain ambiguous welfare prediction which is due to the presence of two opposing effects at work: a positive exploitation effect and a negative intertemporal effect. With Cobb–Douglas production technology, we show that per capita domestic consumption rises in the presence of illegal migration.     

A general endogenous grid method for multi-dimensional models with non-convexities and constraints

The endogenous grid method (EGM) significantly speeds up the solution of stochastic dynamic programming problems by simplifying or completely eliminating root-finding. We propose a general and parsimonious EGM extended to handle (1) multiple continuous states and choices, (2) multiple occasionally binding constraints, and (3) non-convexities such as discrete choices. Our method enjoys the speed gains of the original one-dimensional EGM, while avoiding expensive interpolation on multi-dimensional irregular endogenous grids. We explicitly define a broad class of models for which our solution method is applicable, and illustrate its speed and accuracy using a consumption–saving model with both liquid assets and illiquid pension assets and a discrete retirement choice.     

Measuring digitization: A growth and welfare multiplier

Digitization encapsulates the social transformation triggered by the mass adoption of digital technologies that generate, process and transfer information. The digitization index introduces a global measure of national performance reflecting ubiquity, affordability, reliability, speed, usability and skills. Output and welfare rise with the index while manifesting increasing returns to scale some implications for ICT public policy are drawn from these findings.     

中国城市化与经济增长的省际差异分析

采用聚类分析方法、相关分析方法和回归分析方法,对我国省际城市化水平与经济增长水平的差异进行定量分析,得出以下结论:总体来看,经济发展水平与城市化水平有着较密切的正相关关系;个别地区(如广东)的经济发展水平并不完全与城市化发展水平相适应,经济的发展是由其他因素促成的;天津的城市化水平已经接近极限,而北京和上海的城市化水平仍然有进一步发展的空间;对于落后地区来说,发展经济的重要性更重于狂热地进行城市化.     

首尔的扩张与韩国的城市发展政策

分析了20世纪60年代以来韩国首尔和首尔都市区快速增长的驱动力,回顾了韩国政府的城市增长管理政策,并通过比较数据评析其政策成效.研究韩国的城市增长经验教训,可以为其他快速增长的国家和城市提供有益的启示.     

A two sector endogenous growth model with habit formation

In this paper, we study an endogenous growth model with physical and human capital in which consumption habits enter the utility function multiplicatively. We show that although the utility function with multiplicative habits is nonconcave and unbounded, an interior optimal growth path still exists, it is uniquely determined and it converges to a balanced growth path. We also find that habit formation in consumption lowers the convergence speed of the optimal path toward the balanced growth path.     

Linear programming-based estimators in simple linear regression

In this paper we introduce a linear programming estimator (LPE) for the slope parameter in a constrained linear regression model with a single regressor. The LPE is interesting because it can be superconsistent in the presence of an endogenous regressor and, hence, preferable to the ordinary least squares estimator (LSE). Two different cases are considered as we investigate the statistical properties of the LPE. In the first case, the regressor is assumed to be fixed in repeated samples. In the second, the regressor is stochastic and potentially endogenous. For both cases the strong consistency and exact finite-sample distribution of the LPE is established. Conditions under which the LPE is consistent in the presence of serially correlated, heteroskedastic errors are also given. Finally, we describe how the LPE can be extended to the case with multiple regressors and conjecture that the extended estimator is consistent under conditions analogous to the ones given herein. Finite-sample properties of the LPE and extended LPE in comparison to the LSE and instrumental variable estimator (IVE) are investigated in a simulation study. One advantage of the LPE is that it does not require an instrument.