Formal models of the political resource curse

By surveying formal models, I demonstrate that the political resource curse is the misallocation of revenues from natural resources and other windfall gains by political agents. I show that the curse always exists if political agents are rent-seeking, since mechanisms of government accountability, e.g. electoral competition, the presence of political challengers, and even the threat of violent conflict, are inherently imperfect. However, the scope for rent-seeking becomes more limited as the competition over political power that threatens the incumbent government becomes more intense.     

Regional economic models and continuous programming

This paper is concerned with an optimal investment allocation problem in a simple N-regional economic model. The problem is described as a class of optimal control problem, and formulated into a continuous linear programming problem. Both the primal and dual problems are considered. The procedure finds an optimal regional allocation of investment derived in terms of continuous programming.     

Business incubation models and institutionally void environments

This paper builds a conceptual framework of business incubation models in institutionally void environments, a relevant yet understudied topic in the extant literature. On the basis of a qualitative approach based on the analysis of five case studies drawn from a sample of business incubators in Egypt, and grounding on the literature on institutional voids, we posit that there is a necessity for two different incubation models in institutional laggard environments, typically found in, yet not limited to, developing countries. In particular, we show evidence that the two models supply and facilitate different needs of entrepreneurs, in different stages of entrepreneurial life cycle. We further argue that the incubation model choice is contingent on the incubator sponsors, i.e. affiliation of the incubator, mainly through available resources and imposed objectives. Finally, we offer implications for policy makers who can use the framework to design the regulations in a way that will stimulate appropriate incubator creation and hence sustain local entrepreneurship, as well as for incubator managers who can follow the findings to position their incubation model in line with their resources, capabilities and objectives.     

Structural stability for dynamical economic models

The paper discusses the implications for economics of the notion of structural stability. Definitions are given to characterize dynamical economic models generating movements the qualitative properties of which are conserved under perturbation. Consequences of these definitions, in particular for time evolutions which are globally or locally stable, are then presented through three theorems. Last, two examples — one in micro, one in macroeconomics — illustrate the type of results that can be obtained from such theorems.     

The analysis of seasonal economic models

Many important insights can be obtained about economic relationships and seasonality when an economic model contains an explicit specification of the mechanism generating seasonality in the endogenous variables. Unfortunately, determining the correct structure is difficult. The purpose of this paper is to outline a methodology for the analysis of seasonal economic models. In particular, several ways of incorporating seasonality into a structural model are considered and the implications for the behavior of the endogenous variables are derived. Finally, a rational expectations version of Cagan's money demand function is analyzed to demonstrate some of the important aspects of the techniques and seasonal economic models in general.     

On lags and chaos in economic dynamic models

This paper discusses the role of lags in dynamic economic models. Applications of discrete dynamical systems to economics are considered and the shortcomings of their (implicit) treatment of lags are criticized. An abstract, probabilistic view of lags is then provided, within which fixed delay lags are shown to be a special case. A basic equivalence is proved between: (i) a system with an indefinitely large number of agents, reacting to inputs with randomly gamma distributed, discrete lags, and (ii) a system with one single ‘representative‘ agent reacting to inputs with a continuous, multiple exponential lag. Finally, the paper analyses a single-loop feedback system cuopling a multiple exponential lag and a non-linearity of the one-hump type. The dynamic behavior of the system is studied by means of analytical and numerical methods, and the conditions for periodic and chaotic solutions are investigated.     

论经济发展战略转型与经济发展方式转变

我国"十二五"时期经济社会发展的主线是加快经济发展方式转变,而要加快经济发展方式转变,首要的实现经济发展战略转型。本文首先分析了经济发展战略转型的必然性和基本内容,以及转变经济发展方式的重要性、长期性和主要内容;其次,分析了经济发展战略转型中要处理好的几个关系;最后,提出实现经济发展战略转型和经济发展方式转变,必须以推进技术进步和技术创新为支撑,以深化改革和扩大开放为动力。     

Coherent risk measures in general economic models and price bubbles

In this article we study coherent risk measures in general economic models where the set of financial positions is an ordered Banach space E$E$ and the safe asset an order unit _x0$x_0$ of E$E$. First we study some properties of risk measures. We show that the set of normalized (with respect to _x0$x_0$) price systems is weak star compact and by using this result we prove a maximum attainment representation theorem which improves the one of Jaschke and Küchler (2001). Also we study how a risk measure changes under different safe assets and we show a kind of equivalence between these risk measures. In the sequel we study subspaces of E$E$ consisting of financial positions of risk greater or equal to zero and we call these subspaces unsure. We find some criteria and we give examples of these subspaces. In the last section, we combine the unsure subspaces with the theory of price-bubbles of Gilles and LeRoy (1992).     

Identifying inefficiency in smooth aggregative models of economic growth: A unifying criterion

The paper establishes a complete characterization of inefficient programs in an aggregative model of economic growth. The main theorem states that a feasible program, satisfying a smoothness condition, is inefficient if and only if (a) the sequence of the value of input is bounded away from zero, and (b) the sequence of the ratio of the share of the primary factor in output to the value of input deteriorates too fast. The unifying nature of this result is established by showing that the well-known characterizations of inefficiency, in the literature, are corollaries of the main theorem.     

Null models of economic networks: the case of the world trade web

In all empirical-network studies, the observed properties of economic networks are informative only if compared with a well-defined null model that can quantitatively predict the behavior of such properties in constrained graphs. However, predictions of the available null-model methods can be derived analytically only under assumptions (e.g., sparseness of the network) that are unrealistic for most economic networks like the world trade web (WTW). In this paper we study the evolution of the WTW using a recently-proposed family of null network models. The method allows to analytically obtain the expected value of any network statistic across the ensemble of networks that preserve on average some local properties, and are otherwise fully random. We compare expected and observed properties of the WTW in the period 1950–2000, when either the expected number of trade partners or total country trade is kept fixed and equal to observed quantities. We show that, in the binary WTW, node-degree sequences are sufficient to explain higher-order network properties such as disassortativity and clustering-degree correlation, especially in the last part of the sample. Conversely, in the weighted WTW, the observed sequence of total country imports and exports are not sufficient to predict higher-order patterns of the WTW. We discuss some important implications of these findings for international-trade models.     

The behavior of speculative prices and the consistency of economic models

Modern financial economic theory suggest that changes in speculative prices should follow simple ‘fair game’ processes in an informationally efficient capital market. The observation that changes in speculative prices follow simple time series processes both supports this theoretical proposition and suggest restrictions on the transfer functions of structural econometric models in which speculative prices appear as output variables. The simplicity of the time series processes for observed changes in speculative prices are shown to impose strong restrictions on potential equilibrium models of asset pricing, informational disequilibrium models of financial markets, and many monetary and macroeconomic models as well.     

Smolyak method for solving dynamic economic models: Lagrange interpolation,anisotropic grid and adaptive domain

We show how to enhance the performance of a Smolyak method for solving dynamic economic models. First, we propose a more efficient implementation of the Smolyak method for interpolation, namely, we show how to avoid costly evaluations of repeated basis functions in the conventional Smolyak formula. Second, we extend the Smolyak method to include anisotropic constructions that allow us to target higher quality of approximation in some dimensions than in others. Third, we show how to effectively adapt the Smolyak hypercube to a solution domain of a given economic model. Finally, we argue that in large-scale economic applications, a solution algorithm based on Smolyak interpolation has substantially lower expense when it uses derivative-free fixed-point iteration instead of standard time iteration. In the context of one- and multi-agent optimal growth models, we find that the proposed modifications to the conventional Smolyak method lead to substantial increases in accuracy and speed.     

Verification results for age-structured models of economic–epidemics dynamics

In this paper we propose a macro-dynamic age-structured set-up for the analysis of epidemics/economic dynamics in continuous time.The resulting optimal control problem is reformulated in an infinite dimensional Hilbert space framework where we perform the basic steps of dynamic programming approach.Our main result is a verification theorem which allows to guess the feedback form of optimal strategies. This will be a departure point to discuss the behavior of the models of the family we introduce and their policy implications.     

Nonlinear optimal control of coupled time-delayed models of economic growth

Decisions in Economics and Finance - The article proposes a novel nonlinear optimal control method for the dynamics of coupled time-delayed models of economic growth. Distributed and interacting...     

Specification and estimation of spatial econometric models: A discussion of alternative strategies for spatial economic modelling

The semantical insufficiency of (spatial) economic theories necessitates the making of additional assumptions — thereby introducing substantial specification uncertainty — in order to arrive at a fully specified econometric model. The traditional or current approach to econometric modelling treats specification uncertainty inadequately. This proposition is illustrated by two well-known examples from the spatial economic literature. Two alternative specification strategies for spatial economic modelling — designed to improve the current spatial econometric modelling approach — are proposed. One of these strategies is used for a specification analysis of agricultural output in Eire.