Bootstrap prediction intervals for autoregressions: some alternatives

A new method is proposed to obtain interval forecasts for autoregressive models taking into account the variability due to the estimation of the order and the parameters. The procedure improves that introduced by Masarotto (1990), allows a substantial reduction of the variance of the predictive distribution percentile estimators and should thus be considered as a useful alternative to the classic Box and Jenkins interval forecast. The method uses the bootstrap technique and is distribution-free. An empirical application is considered.     

Popular movements and urban alternatives in post-Franco Spain

L'Espagne se trouve à l'encontre de sévères problèmes urbains que le régime authoritaire ne peut résoudre. Au fǔr et à mesure que ce régime se désintère, de nouvelles revendications surgissent; mais en Espagne, contrairement au Portugale, ce sont des mouvements organisés qui réclament une nouvelle politique. Ces mouvements populaires sont fondés sur les quartiers (Barrios); cette communication s'addresse à leurs développement à Barcelone. Les mouvements urbains de cette ville ont évolués à partir d'une contestation d'issus d'envergure locale, à une qui s'addresse aux processus et planification de toute la ville. Un réseau de groupes a créé les moyens pour une renaissance d'une vie collective et démocratique. Le droit à un logement convenable, aux aménagements adéquats, au contrǒle sur l'industrie et la pollution, et à une suspension des rénovations urbaines, s'est fait valoir. Les moyens par lequels ces objectifs sont accomplis sont esquissés. Une critique de la planification implique celle de l'administration municipale. Divers genres de protestations ont eu lieu à différentes périodes dans l'évolution de cette critique. C'est maintenant que les mouvements communautaires, les analystes de l'urbain, et les nouveaux groupes politiques ont besoin de travailler ensemble afin développer un nouveau contexte pour le gouvernement municipal, à l'intérieur d'un programme socio-économique plus large. Dans n'importe quel système futur, les groupes des Barrios continueront de jouer un rǒle essentiel. Un mouvement vers une réforme municipale accompagnera vraisemblablement un changement social plus grand, surtout celui de la lutte pour l'autonomie Catalane.     

轨道交通对城市空间形态的影响

从轨道交通线网、轨道交通站点与空间形态、轨道交通与城市发展轴、轨道交通与城市中心等四个方面讨论了轨道交通对城市空间形态的影响.     

A forecasting comparison of some var techniques

Higher dimensional multivariate time series models suffer from the problem of over-parametrisation which impairs their forecasting performance. Starting from such unrestricted vector autoregressive models the paper discusses two ways to cope with this difficulty. The first approach reduces the number of free parameters by applying a subset modelling strategy. The second approach takes a Bayesian point of view by formulating ‘priors’ which are then combined with sample information, but leaving the original specification unaltered. Using Austrian quarterly macroeconomic time series a comparative study is undertaken by running alternative forecasting exercises. Both methods improve out-of-sample forecasting performance substantially at the cost of some bias in ex-post simulations. Comparing the ex-ante predictions of the two approaches, the former does better at short horizons whereas the latter gains as the forecast horizon lengthens.     

城市轨道交通车辆制动方式综述

改革开放以来,我国经济高速发展,城市面貌日新月异,我国城市化进程明显加快,机动车数量增加迅猛,这就带来了如何缓解城市交通拥堵、减小环境污染、解决能源危机等一系列问题。城市轨道交通车辆的速度可以达到公共汽车的3倍;安全、准点率高,给上班族提供了时间保障;轨道交通采用电力牵引,能源利用率高,环境污染少。但由于城市轨道交通车站之间的距离大约1 km左右,所以车辆需频繁的调速和制动,对车辆的制动有较高的要求。因此,文章主要讲述了城市轨道交通车辆采用的几种制动方式。     

Regional taxonomy : A comparison of some hierarchic and non-hierarchic strategies

The effects of subjective decisions, particularly in the case of regional taxonomic methodology are often underestimated. Therefore the aptitude of alternative methods needs more careful evaluation. Comparisons of competing methods would provide important guidelines. A general evaluative approach based upon the discrepancy between the original resemblance and the derived cophenetic matrix is outlined for the hierarchic regional taxonomic case. Five main aggregative linkage strategies are appraised by means of quantitative measures. Furthermore two iterative non-hierarchic methods are compared for handling non-hierarchic regional taxonomic problems, where particular attention is paid to the influence of different initial partitions upon the (sub) optimal result.     

Urbanization in some hierarchical urban models

"This paper examines two aspects of hierarchical urban models: the variations of total urban population and that of the urbanization ratio, in function of the number of hierarchical levels. Both variations are analysed through four categories of models. The complexity of the results suggests two approximations in order to make the analysis more tractable."     

城市发展中的文化自觉与文化创新——以"新天地"为例

在城市现代化进程中,如何处理好历史文化与城市改造之间的关系是显示城市文明程度和关系到城市文化发展的重要课题.以上海"新天地"区域的改造模式为案例进行文化层面的解读,力图阐明城市发展中文化自觉与文化创新的必要性和实践性,分别从实例分析和理论阐释层面指出,建立在认识自我和借鉴他者基础上的文化自觉精神和文化创新实践是城市文化发展的必由之路.     

城市创新系统理论研究综述

首先,阐明并追溯了城市创新系统的定义、学术史渊源和理论来源,其后,从组织结构、功能特征、运作机制、系统构建、评价体系等方面对城市创新系统研究进行了回顾和理论总结,并指出了当前研究中存在的问题.     

Optimal error and GMDH predictors: A comparison with some statistical techniques

This paper presents some results obtained in time series forecasting using two nonstandard approaches and compares them with those obtained by usual statistical techniques. In particular, a new method based on recent results of the General Theory of Optimal Algorithm is considered. This method may be useful when no reliable statistical hypotheses can be made or when a limited number of observations is available. Moreover, a nonlinear modelling technique based on Group Method of Data Handling (GMDH) is also considered to derive forecasts. The well-known Wolf Sunspot Numbers and Annual Canadian Lynx Trappings series are analyzed; the Optimal Error Predictor is also applied to a recently published demographic series on Australian Births. The reported results show that the Optimal Error and GMDH predictors provide accurate one step ahead forecasts with respect to those obtained by some linear and nonlinear statistical models. Furthermore, the Optimal Error Predictor shows very good performances in multistep forecasting.     

The relationship between R&D,innovation and productivity in emerging economies: CDM model and alternatives

CDM (Crépon, Duguet and Mairesse, 1988) is a workhorse model in the economics of innovation, which explains productivity in a three-stage procedure driven initially by R&D and leads to patents and then to productivity improvements. Based on the logic of this model, an increasing number of papers applies it to emerging economies but modifies the original model without being explicit about the nature and implications of this modification. We argue in this paper that, in its original form, CDM does not capture stylized facts of the determinants of productivity in emerging economies and that we need alternative models. Accordingly, we are critical of papers that try to maintain the validity of the model but actually change it. For that purpose, we test the original CDM model and its two alternatives: investment and production capability–driven models. Our research is based on a large sample of firms in Central and Eastern Europe, former Soviet republics and Turkey, and we show that the alternative models are much closer to the stylized facts of innovation activities and technology upgrading in these and other emerging economies. Our conclusions have important policy implications, which we discuss.     

Allowing for inefficiency in parametric estimation of production functions for urban transit firms

Efficient versus inefficient observations are first identified and evaluated numerically by the nonparametric free disposal hull (FDH) method. Next, parametric production frontiers are obtained by means of estimating translog production functions through OLS applied to the subset of efficient observations only. Technical progress is included at both stages. Monthly data from three urban transit firms in Belgium, to which this two-stage technique is applied, show widely varying degrees of efficiency over time and across firms, and much less technical progress than standard (i.e., non frontier) econometric estimates suggest.     

A description of some factors affecting technological innovation in industry in the United Kingdom and some remedies to improve the climate

The change of innovation and its successful implementation at the industrial levels are important features of economic development and, therefore, are of great significance for the future of industries. This paper concentrates on the analysis of the past performance of industries in the U.K., which has shown a decline in technological innovation and international trade when compared to other industrial countries. The first section of the paper considers the channels for exploration of new technology with the aid of established companies, new companies and the public sector. The second half of the paper considers the factors affecting technological innovation such as economic conditions, size of market, sources of finance, patents and licensing. The paper concludes with several suggested recommendations for policy changes to improve directly or indirectly the incentives for technological innovation in the industries of the U.K.     

科技成果转化与技术创新:创新范式的比较与转变探讨

如何发挥科学技术的强大经济功能,国内外存在着科技成果转化和技术创新两种思维范式;科技成果转化的思维范式带有明显的机械论思维特征和计划经济特征,在现代市场经济条件下存在明显的机制性缺陷;在创新驱动发展战略中必须确立技术创新的范式,实现由科技成果转化范式向技术创新范式转变。     

The possible adverse impact of innovation subsidies: some evidence from Italy

The impact of public funding on innovative productivity is estimated using a sample of Italian firm-level data (CIS3). A bivariate endogenous switching model is developed in order to free the analysis of the sources of sample selection and firm heterogeneity, the possible simultaneity between subsidy allocation and the qualitative composition of the innovative output, as well as the endogeneity of public support with respect to innovative performance. Results show that innovative productivity is negatively affected by the subsidy; as a result of government intervention, supported firms appear to exhaust their advantage through merely increasing their innovative expenditures.     

城市轨道交通次生环境影响评价指标体系建构

城市轨道交通项目的建设给城市的经济环境、社会环境和自然环境带来极大的次生环境影响,因此有必要对城市轨道交通次生环境影响进行切合实际的综合评价.在总结城市轨道交通次生环境影响评价基本特点的基础上,构建了城市轨道交通次生环境影响评价指标体系,给出了各个评价指标的量化方法和评价标准,从多个方面论证了城市轨道交通的正面效益更多地体现在其对城市的次生环境影响中.这一结论的得出为建立和完善城市轨道交通次生环境影响评价理论,正确进行城市轨道交通项目投资决策奠定了的基础.     

德国城市规划的制度创新——环境鉴定与环境报告制度

随着2004年德国新版<建设法典>的颁布实施,德国城市规划制度引入了法定的环境鉴定和环境报告制度,成为德国城市规划的又一项制度创新.介绍了<建设法典>中关于环境鉴定和环境报告制度出现的背景及其主要章节,分析了其环境鉴定和环境报告的要点,并阐述了结合环境鉴定和环境报告的德国城市规划编制的新程序.