Demographic processes in a model of innovation diffusion with dynamic market

In this paper we study a binomial innovation diffusion model for a variable size market by modelling the demographic process of entrance-exit from each market compartment. We examine from a theoretical point of view the effect of the simultaneous presence of economic and demographic parameters under the exponential market growth hypothesis, by presenting some general results on the adoptions and sales time path. We also enlighten the relevance of considering these variables in relative terms and show how, in presence of a dynamic, the diffusion process never saturates the market. Finally, we test our model on a data set for cellular phones market in different countries.     

Analysis on the growth of telecommunication services: a global comparison of diffusion patterns

With the development of the Internet, the telecommunication market has seen a rapid shift from voice-based services to data-based services. Relationships of substitutability and complementarity have emerged among communications technology services such as Internet service, mobile phone service and fixed telephone service. The article analyses the diffusion patterns of communication services in different continents. A modified logistic growth model is estimated using panel data for the years 1975–2004. The research forms a valuable framework for forecasting demand for new services based on the diffusion of incumbent services and can inform strategies for entering the communications network industry.     

The value of money in a dynamic equilibrium model

Summary. This paper studies the pricing of money in an infinite-horizon economy with heterogeneous agents, incomplete financial markets and arbitrary borrowing restrictions. Purchases of the consumption good are subject to a cash-in-advance constraint. Under general conditions I show that the price of money is equal to its fundamental value, where this value is defined over all state-price processes that are compatible with the existence of no-arbitrage opportunities. This equality implies that the cash-in-advance constraint is binding infinitely often for all agents in the economy. The analysis highlights certain differences in the determination of the price of money with respect to models with money in the utility function that bear on the optimal implementation of economic policies.Received: 23 October 2003, Revised: 26 August 2004 JEL Classification Numbers: D52, E44, G12.M.S. Santos: This paper is an outgrowth of an earlier collaboration with Michael Woodford. I have also benefitted from various discussions with Eduardo Gimenez, Alejandro Hernandez, and Miguel Iraola. Some very useful comments by an anonymous referee are greatly appreciated.     

电信服务业:山雨欲来风满楼

伴随着改革开放的发展1980年以前，我国电信业由政府部门直接垄断经营，国家对电话资费实施严格管制，电信业基本不赢利甚至亏损，电信基础设施及服务短缺。改革开放后，政府开始实施电信管理体制改革并放松价格管制，实行中央和地方双重领导、允许邮电部门征收电话初装费等措施。这些政策促进了电信业的迅速发展。1979年—1995年，全国邮电通信固定资产投资达2700亿元（其中约1/3来自电话初装费）。电信业的真正改革是在1994年成立中国联通公司，打破了原中国电信长期独家垄断国内电信市场的局面。电信市场的发展、开放和变革大致经历了以…     

Minorities and majorities: a dynamic model of assimilation

Abstract.  The paper analyses the population dynamics of a country that has two ethnic groups, a minority and a majority, and minority members can choose to assimilate into the majority. Depending on the minority's size, the long‐run outcome can be full or no assimilation. Under certain parameter values multiple equilibria exist, including the two extreme cases. The paper demonstrates that both the long‐run outcome and the equilibrium path may be inefficient. Two extensions to the basic model are considered. The first one allows for a comparison between a multicultural and a 'melting pot' society. The second one introduces population growth and studies the interplay between exogenous and endogenous changes in the minority's size. JEL classification: J110, J150, J180     

Price and quantity adjustment in a dynamic closed model: The dual stability theorem

The paper analyzes dual instability in a dynamic input-output framework. It is divided into three parts: the first gives an informal introduction, the second discusses the similarity with the knife edge, and the last suggests a new interpretation, which guarantees nonnegative solutions and relative stability. It has been assumed that the producers adjust their prices following an adaptive expectation mechanism, and the current level of investment to the expected value defined by a golden rule approach.     

The diffusion of successive generations of a technology: A more general model

In many cases of technological development, successive generations of a technology evolve, each more efficient than its predecessor. It has been assumed when modeling and forecasting the adoption of these technologies that the market reaction to each generation was similar. Using the terminology of the Bass model, this similarity is encapsulated in the assumption that the coefficients of innovation and imitation are constant. New data for two and three generations of mobile telephone technology from eleven countries are modeled. The modeling framework used—simultaneous estimation for successive generations using a full information maximum likelihood procedure—demonstrates that, in most cases, the hypothesis of constant coefficients can be rejected. Use of a model with changing coefficients is shown to considerably improve forecasting performance. These results were reinforced by analysis of data for four generations of IBM mainframes.     

A percolation model of eco-innovation diffusion: The relationship between diffusion, learning economies and subsidies

An obstacle to the widespread adoption of environmentally friendly energy technologies such as stationary and mobile fuel cells is their high upfront costs. While much lower prices seem to be attainable in the future due to learning curve cost reductions that increase rapidly with the scale of diffusion of the technology, there is a chicken and egg problem, even when some consumers may be willing to pay more for green technologies. Drawing on recent percolation models of diffusion, we develop a network model of new technology diffusion that combines contagion among consumers with heterogeneity of agent characteristics. Agents adopt when the price falls below their random reservation price drawn from a lognormal distribution, but only when one of their neighbors has already adopted. Combining with a learning curve for the price as a function of the cumulative number of adopters, this may lead to delayed adoption for a certain range of initial conditions. Using agent-based simulations we explore when a limited subsidy policy can trigger diffusion that would otherwise not happen. The introduction of a subsidy policy seems to be highly effective for a given high initial price level only for learning economies in a certain range. Outside this range, the diffusion of a new technology either never takes off despite the subsidies, or the subsidies are unnecessary. Perhaps not coincidentally, this range seems to correspond to the values observed for many successful innovations.     

The dynamic effectiveness of monetary policy in China: evidence from a TVP-SV-FAVAR model

We use a broad set of China’s macroeconomic indicators and a dynamic factor model to estimate latent factors of economic output and inflation, which are used to measure the ultimate objectives of monetary policy. The above factors and policy variables are incorporated into a TVP-SV-FAVAR model to investigate the dynamic effectiveness of Chinese monetary policy. Our results confirm that the effects of Chinese monetary policy are time-varying. By comparing the quantity rule with the price rule, we find that the price rule is more effective in managing China’s macro-economy, especially after the financial crisis. Moreover, the results can be regarded as a division of policy rules in a way that different rules are directed at different objectives.     

Knowledge, hierarchy and the selection of routines: an interpretative model with group interactions

The aim of this paper is to analyze the selection of routines inside an organizational structure characterized by different cognitive representations and facing hierarchical pressure leading to either truce or conflict. After a brief discussion of the role of hierarchy and the related problems of organizational practice selection in the evolutionary literature, we model the interactions between different groups within a firm trying to interfere with its coordination mechanisms in order to support their own practices. Numerical simulations highlight the different learning abilities present in various organizational set-ups and their related knowledge distribution. It is shown that networking designs are the most profitable organizational configurations because of their dynamics of learning, though they are very sensitive to the truce problem.JEL Classification: L14, L20, L22, B52, D83Correspondence to: Nathalie Lazaric     

Indeterminacy in a dynamic two-country model

The purpose of this paper is to show that indeterminacy can arise in a simple competitive two-country dynamic model of international trade, free of externalities, imperfect competition, and government intervention. This seemingly surprising result is based on an assumption that there is no international credit market. As will be shown later, the assumption implies that dynamic equilibrium paths of our two-country, therefore heterogeneous consumer, model are not generally Pareto-optimal.The paper is dedicated to Professor Mukul Majumdar on the occasion of his 60th birthday with great respect. We thank Takashi Kamihigashi, Tapan Mitra and Makoto Yano for their useful comments on the earlier version of this paper.     

Donations in a recursive dynamic model

Abstract.  This paper studies how donations respond to unexpected permanent changes in income and tax rates in a recursive dynamic model. The dynamic approach yields several interesting insights. If marginal tax rates are progressive, a permanent jump in a household's income increases its consumption and donations in the short run, but has no effect in the long run. The permanent income elasticity of current donations is likely to exceed one. If the marginal tax rate is flat, the jump in income raises consumption and donations in both the short and the long run. A permanent marginal tax rate cut raises consumption and donations in the long run if marginal tax rates are progressive, while it reduces donations in the short run if it has little direct impact on tax payments. If the marginal tax rate is flat, a tax cut has a positive effect on consumption in both the short and the long run, but has an ambiguous effect on donations.     

Price-raising drug enforcement and property crime: a dynamic model

Price-raising drug enforcement suppresses drug use, but it is expensive and may increase property crime. This has led to contradictory recommendations concerning how drug enforcement should or should not be used. We reconcile these recommendations by incorporating the enforcement's effects on both drug use and on property crime within an optimal-control model that recognizes whether convicted drug-involved property offenders are merely incarcerated or whether they receive some form of drug treatment.     

Controlling a biological invasion: a non-classical dynamic economic model

This paper analyzes the optimal intertemporal control of a biological invasion. The invasion growth function is non-convex and control costs depend on the invasion size, resulting in a non-classical dynamic optimization problem. We characterize the long run dynamic behavior of an optimally controlled invasion and the corresponding implications for public policy. Both control and the next-period invasion size may be non-monotone functions of the current invasion size; the related optimal time paths may not be monotone or convergent. We provide conditions under which eradication, maintenance control, and no control are optimal policies.      

Optimal compliance with emission constraints: dynamic characteristics and the choice of technique

The paper analyzes how to comply with an emission constraint, which restricts the use of an established energy technique, given the two options to save energy and to invest in two alternative energy techniques. These techniques differ in their deterioration rates and the investment lags of the corresponding capital stocks. Thus, the paper takes a medium-term perspective on climate change mitigation, where the time horizon is too short for technological change to occur, but long enough for capital stocks to accumulate and deteriorate. It is shown that, in general, only one of the two alternative techniques prevails in the stationary state, although, both techniques might be utilized during the transition phase. Hence, while in a static economy only one technique is efficient, this is not necessarily true in a dynamic economy.      

The direct estimation of the equilibrium response in a linear dynamic model

It is shown that any linear dynamic model can be written in a form which enables the equilibrium multipliers to be estimated directly. Furthermore, these estimates are directly equivalent to those derived from the unrestricted reduced form.     

Specification and estimation of a dynamic disequilibrium model

A disequilibrium model is considered, in which unsatisfied demand or supply in any given period carries over into the next period. An estimation procedure based on a LIML approach is then suggested.     

Inequalities and fluctuations in a dynamic general equilibrium model

   Summary. In the present paper a tractable two-sector neo-classical growth model with heterogeneous agents is considered. The local dynamic properties of the equilibrium path are analyzed in relation with the underlying characteristics of the economy. In particular, the existence of fluctuations is related to the degree of heterogeneity in labor and in capital endowments. When applied to international trade theory, the analysis shows that free trade may distabilize a world economy that is originally stable under the regime of autarky. Received: December 28, 1998; revised version: October 29, 1999     

Optimal disaster-preventive expenditure in a dynamic and stochastic model

The purpose of this study is to present an analytical framework for publicly optimal disaster-preventive expenditure. We examine the optimal policy combination of tax rate, disaster-preventive expenditure, and productive government expenditure in a neoclassical growth model, in which natural disasters occur stochastically and partially destroy existing capital. Based on this model, we can decompose the welfare effect of raising preventive expenditure into three effects: the damage reduction, crowding out, and precautionary effects. By identifying these marginal benefits and costs, we obtain the policy conditions that maximize household welfare. Furthermore, we show that optimal prevention is increasing in disaster probability, and by using a numerical example, we show that there is an inverse U-shaped relationship between the expected growth rate and disaster probability.