Accommodating spatial correlation across choice alternatives in discrete choice models: an application to modeling residential location choice behavior

This paper presents a modeling methodology capable of accounting for spatial correlation across choice alternatives in discrete choice modeling applications. Many location choice (e.g., residential location, workplace location, destination location) modeling contexts involve choice sets where alternatives are spatially correlated with one another due to unobserved factors. In the presence of such spatial correlation, traditional discrete choice modeling methods that are often based on the assumption of independence among choice alternatives are not appropriate. In this paper, a Generalized Spatially Correlated Logit (GSCL) model that allows one to represent the degree of spatial correlation as a function of a multi-dimensional vector of attributes characterizing each pair of location choice alternatives is formulated and presented. The formulation of the GSCL model allows one to accommodate alternative correlation mechanisms rather than pre-imposing restrictive correlation assumptions on the location choice alternatives. The model is applied to the analysis of residential location choice behavior using a sample of households drawn from the 2000 San Francisco Bay Area Travel Survey (BATS) data set. Model estimation results obtained from the GSCL are compared against those obtained using the standard multinomial logit (MNL) model and the spatially correlated logit (SCL) model where only correlations across neighboring (or adjacent) alternatives are accommodated. Model findings suggest that there is significant spatial correlation across alternatives that do not share a common boundary, and that the GSCL offers the ability to more accurately capture spatial location choice behavior.     

央企的公司绩效更优吗?——来自2007-2009年中国证券市场的经验证据

鉴于央企近几年来表现的出色业绩,本文选取2007-2009年沪深两地A股上市公司作为研究样本,按企业性质的不同将其分为央企公司、非央企国有公司和私人公司三类,通过对其盈余能力、盈余管理水平、市场反应及在职消费的比较,实证检验了企业性质是否直接影响了公司绩效。结论表明:在所有上市公司中,央企公司绩效最差,非央企国有公司次之,私人公司绩效最好。最后对此结论进行了初步的分析,并指出:只有始终不渝地加快市场化改革进程才是提高包括央企在内的国有企业绩效的必由之路。     

区位商视角下的深圳优势产业实证分析

深圳经济特区成立30年以来,经济快速发展的同时也面临各种挑战。一方面,深圳内部面临着发展后劲不足、调控经济不力等多方面的问题;另一方面,外部经受着国内产业结构不断优化升级的考验。运用区位商对深圳的产业优势进行数量上的分析,可以为深圳产业结构的调整和转型提供科学指导,加速深圳的产业结构升级,以促使深圳的经济能够跃上新的台阶。     

Can farmers extend their cultivation areas in urban agriculture? A contribution from agronomic analysis of market gardening systems around Mahajanga (Madagascar)

The rapid urbanization in developing countries implies an increasing pressure on urban agriculture for production. As most perishable food products come from this agriculture in close proximity to population concentrations, we analysed from an agronomic point of view how market-garden farmers can meet this increasing urban demand. This work took place in the case of Mahajanga, a secondary city with high increasing demographic rate on the Northwest coast of Madagascar. Based on preliminary surveys to characterize the farming systems (on a sample of 91 farms), 11 market-garden farmers chosen in the three main agricultural zones of the urban area were surveyed during two years. Surveys aimed at understanding their decision rules in crop choices, crop allocation to land and resource management, and to estimate their room for manoeuvre to increase their leafy vegetable areas under cultivation. The wholesalers and retailers who buy the farmers’ produce were also surveyed. A previous model of decision rules regarding crop location on farm territory was used to analyse the on-farm surveys and cartographic methods (GIS and on-farm manual representations) were used to quantify the land use. We highlight the following major points. (1) The leafy vegetable production in the surveyed farms already intensively uses land: farmers have complex decision rules largely depending on the water dynamics in the two main environments (lowlands and lakesides) where leafy vegetables are cultivated during the dry season. (2) The scarcity of farmers’ resources (labour money and water) leads to very little internal room for manoeuvre to increase the leafy vegetable production in the farms. (3) At territorial level however, some land reserve exist in one of the lowlands, but not on lakesides. The water availability for agriculture must be better informed through specialized hydrologic studies, as one of the main constraints nowadays to extend the agricultural area. An extrapolation to other cases of urban agriculture is then discussed as well as the role of agronomy to help urban planners to consider the place of agriculture in the urban development.     

我国纺织服装业投资东盟的区位选择

纺织品配额取消以后,我国纺织服装出口反而遇到前所未有的挑战,纺织服装的低成本优势正在逐步丧失。为了化解出口压力,作为纺织服装出口大国,我国应该借助中国东盟自由贸易区(CAFTA)建设的机遇,把低端产品的生产转移到东盟。     

房地产营销定位新概念

从房地产营销定位的产生与发展入手 ,进而从理论上阐述了心理定位对房地产营销的意义 ,并从心理学角度讨论了心理定位对消费者的影响。还通过大量实例分析 ,进一步论述了心理定位的方法及策略     

基于周期的低轨预警系统任务动态重规划策略

根据预警系统资源的特点和导弹跟踪任务的实时性和不确定性,天基低轨预警系统 任务规划具有动态性的特点。为解决低轨系统动态任务规划问题,提出了低轨预警系统动态 任务规划模式,分析了周期重规划调度策略,探讨了系统动态重规划中重规划周期的确 定方法,并对其中的弹道预测误差椭球和双星定位精度两个关键问题进行了建模,为动态问 题建模求解提供基础。     

汉语方言中来源格、处所格和目标格融合现象初探

本文通过对汉语38个方言点中49组介词融合(syncretism)现象的考察,发现汉语来源格、处所格和目标格之间的融合现象可以通过两种融合模式加以说明。其一是双向融合模式,即处所格和来源格可以双向融合,处所格和目标格也可以双向融合,因此出现三个格用一个词表示的语言现象,在这种模式中来源格与目标格融合需要另外解释。其二是单向循环融合模式,即处所格发展出目标格,目标格发展出来源格,来源格再发展出处所格,形成一个循环。汉语方言中来源格、处所格和目标格存在错综复杂的关系可能是多种因素综合作用使然。     

零售企业扩张实践质疑威廉姆森命题

"复制和选择性干预不可能",是威廉姆森关于企业规模边界的一个颇具权威性的命题,但是本文认为,这个命题已遭到零售企业扩张实践的质疑,沃尔玛、家乐福等零售企业的扩张恰恰是由"复制和选择性干预"所支撑的.本文从零售企业"类似性活动"业务属性和"订购性生产"经营特征分析切入,对零售企业扩张中"复制和选择性干预"成为可能的深层原因进行了探讨.最后,文章认为,威廉姆森命题的遭遇与经济学的某种局限有关,这种局限的直接表现是经济学一直都将企业默认为生产企业,忽略流通企业的特殊属性,"工商合一"、"以工代商".文章对这种表象背后的原因也作了一定的分析.     

董事会的独立性是否影响公司绩效?

在董事会和公司绩效的研究框架内,代理理论和乘员理论就独立董事比例的绩效后果产生了分歧,前者认为独立董事通过降低代理成本促进绩效,后者则认为董事会效率会因独立董事比例的提高而下降。利用中国资本市场的数据,本文系统地检验了董事会独立性和公司绩效的关系,为这一争议提供了证据。研究发现,独立董事比例和公司绩效显著正相关,这种相关性在控制内生性问题后仍然成立,并且发现当大股东缺乏制衡时,独立董事比例对公司绩效的促进作用会显著降低,这一结果表明代理理论对中国资本市场的公司治理更具解释力。我们还进一步就独立董事的背景和公司绩效的关系进行了检验,研究发现独立董事的声誉能够显著地促进公司绩效,而其行业专长、政治关系以及经济管理背景与公司绩效并无相关性。