Estimating exchange rate dynamics with diffusion processes: an application to Greek EMU data

Recently various exchange rate models capturing the dynamics during the transition from an exchange rate arrangement of floating rates into a currency union have been derived. Technically, these stochastic equilibrium models are diffusion processes which have to be estimated by discretely sampled observations. Using daily exchange rate data prior to the Greek EMU-entrance on 1 January 2001, we develop a rigorous estimation procedure. Our estimates point to an increasing interventionist economic policy in the run-up to the Greek EMU entrance. A comparison of this econometric indication with policy information provided (ex-post) by the Bank of Greece (BoG) in its Annual Report 2000 reveals that the BoG indeed pursued such an active policy stance (so-called institutional frontloading strategies).      

World Oil Depletion Models: Price effects compared with strategic or technological interventions

World oil depletion, including natural gas liquids, was modelled in the past by many authors. Recently, Guseo and Dalla Valle have introduced and Guidolin has applied a new approach following perturbed life-cycle diffusion models. Here we examine joint effects of economic and strategic or technological interventions using a Generalized Bass Model (GBM). Statistical analysis takes into account three different hierarchical levels: natural diffusion, long memory interventions and stochastic components. The main results confirm the statistical significance of historical 1970s shocks and highlight a strong long memory effect due to an increase in oil production after World War II. The estimated peak-date, 2007, and the 90% depletion time, 2019, are determined under an equilibrium intervention hypothesis.     

我国智慧城市创新扩散演进机理及启示

基于政策创新扩散理论,从城市内外两方面构建智慧城市扩散影响模型,运用事件史分析方法对38个城市数据进行分析。研究发现：在城市内部因素中,城市规模、人口密度和人均收入未对智慧城市扩散产生显著影响,城市性质和经济实力对智慧城市扩散产生显著正向影响;在城市外部因素中,城市间政府竞争和府际学习是智慧城市扩散发生的关键因素,但上级压力假设未获得支持。     

A model of multiple-unit ownership as a diffusion process

This paper develops and tests a new model for multiple-unit adoptions of durable goods based on the diffusion modeling tradition. Multiple-unit adoptions are a major component of sales for many consumer durable product categories. For instance, sales of multiple-unit adoptions for televisions have been higher than both first adoptions and replacement purchases since 1977, while for automobiles, they have represented more than 20% of sales since 1966 in Australia. The structural drivers of multiple-unit adoptions are quite different from either first purchase or replacement purchase. Hence, identifying and modeling the multiple-unit component of sales is important for aggregate sales forecasts. Moreover, consumer requirements for additional units of a product are likely to be considerably different than for the other components of sales (first purchases and replacement purchases). As such, the ratio of the first, multiple, and replacement sales components will strongly influence the product mix requirements of the market.

While forecasting and influencing multiple-unit sales are an important managerial issue, very little attention has been given to multiple-unit ownership in the diffusion modeling literature. The only model available was developed for the purpose of modeling relatively short-term behavior of multiple-unit adoptions, rather than the longer-term pattern of sales. We propose a model of multiple-unit adoptions as a diffusion process.

We apply the model to both color television and automobiles. Analysis of the model's long-term fit and forecasts in these applications provide support for the structure of the new model.     

颠覆性创新四阶段扩散过程模型

基于颠覆性创新、创新扩散、创新模糊前端等相关理论,从全流程角度创新性地构建了颠覆性创新四阶段扩散过程模型,包括颠覆性创意产生、颠覆性创新产品开发、侵蚀非主流市场、占据主流市场4个阶段,各阶段之间相互关联、循环往复,并受到技术、市场、政策、竞争等外部环境因素影响。选取液晶电视机和山寨手机作为高端和低端两个颠覆性创新典型案例,通过对其进行验证性分析,构建具体的高端与低端颠覆性创新四阶段扩散过程模型。     

基于指数随机图模型的专利技术扩散机制实证研究

网络嵌入视角下专利技术扩散路径间存在相关性,但这种网络内生性影响并未在已有研究中得到足够重视。将扩散因素归纳为：专利价值、专利保护、多维同配、结构嵌入,从扩散网络内生、外生因素两个方面构建分析模型,并以石墨烯领域为例,采用指数随机图模型,开展实证研究。实证结果说明：专利价值、技术、地理、组织层面同配性、闭合三角结构嵌入均正向促进专利技术扩散,而专利保护强度反向抑制技术扩散。值得注意的是,专利技术扩散存在强烈的结构嵌入倾向,融合网络内、外生因素的模型能够更好地捕捉专利技术扩散机制。     

Localized innovation, localized diffusion and the environment: an analysis of reductions of CO2 emissions by passenger cars

We investigate technological change with regard to CO₂ emissions by passenger cars, using a Free Disposal Hull methodology to estimate technological frontiers. We have a sample of cars available in the UK market in the period 2000–2007. Our results show that the rates of technological change (frontier movement) and diffusion (distance to frontier at the car brand level) differ substantially between segments of the car market. We conclude that successful policies should be aimed at the diffusion of best-practice technology, and take account of the different potential for further progress between different segments of the market (e.g. diesel vs. gasoline engines and small vs. large engines).

Boosting the spread of new technologies: an integrative propositional analysis of diffusion policies

ABSTRACT

Although many studies have recognised the importance of defining specific public policies to encourage technology diffusion, many authors fail to provide a clear view about either the policies that affect the diffusion of technologies or the effect of the different political instruments. Adopting a content analysis of papers that directly or indirectly refer to the diffusion of a new technology, this study applies the integrative propositional analysis (IPA) methodology to: (a) identify the repertoire of the different diffusion policies identified by previous studies; (b) classify these policies according to the type of instruments that they use; (c) analyse the impact of each policy on the different adoption factors that may inhibit or foster the diffusion of a new technology; and (d) evaluate the scope of each type of policy in terms of the number of affected adoption factors.     

A statistical equilibrium model of competitive firms

We find that the empirical density of firm profit rates, measured as returns on assets, is markedly non-Gaussian and reasonably well described by an exponential power (or Subbotin) distribution. We start from a statistical equilibrium model that leads to a stationary Subbotin density in the presence of complex interactions among competitive heterogeneous firms. To investigate the dynamics of firm profitability, we construct a diffusion process that has the Subbotin distribution as its stationary probability density. This leads to a phenomenologically inspired interpretation of variations in the shape parameter of the Subbotin distribution, which essentially measures the competitive pressure in and across industries. Our findings have profound implications both for the previous literature on the ‘persistence of profits’ as well as for understanding competition as a dynamic process. Our main formal finding is that firms' idiosyncratic efforts and the tendency for competition to equalize profit rates are two sides of the same coin, and that a ratio of these two effects ultimately determines the dispersion of the equilibrium distribution.     

全球化对城市空间结构的作用机制分析

论文认为城市空间结构的演进归根结底是微观经济主体,尤其是企业的生产行为和区位选择行为推动的。企业对生产组织和空间布局的不同选择,直接影响着两种不同的空间发展模式——集中化和分散化。全球化和信息化推动了生产技术方式和生产组织方式的演进,对企业区位选择、产业的空间布局,以及城市空间结构和空间组织产生了重要影响,都市圈、城市群成为当今先进生产组织方式的重要空间载体。