中国城市科技人才集聚促进了全要素生产率增长吗——来自285个地级市的经验研究

基于2005—2018年中国内地285个地级市数据，对城市科技人才集聚与全要素生产率（简称“TFP”）进行测度分析，实证考察科技人才集聚对TFP的影响。结果表明：①城市科技人才集聚与TFP空间分异特征显著，但二者具有较强的时空一致性，即科技人才集聚特征显著的城市，其TFP也相对稳定；②城市科技人才集聚对TFP的影响呈倒U型，但研究期内大多数城市仍处于集聚效应占主导阶段,科技人才集聚通过提升城市技术进步水平促进TFP增长，而科技人才集聚对技术效率的影响呈倒U型；③不同类型城市科技人才集聚对其TFP影响的异质性显著，且适宜集聚区间也存在差异。省会城市及一、二线城市等优势特征显著的城市所能承受的科技人才集聚规模上限更高，有利于通过释放集聚红利促进TFP增长，而非省会城市、三线及以下城市等则拐点值较低。     

产业集聚结构与城市经济增长的非线性关系

随着我国城市化进程的加速,产业集聚给城市经济带来了多层面的影响。基于理论上的可能性,本文提出产业集聚与城市经济增长的非线性假设,并使用我国城市数据和Panel 2SLS计量模型加以验证。我们将城市产业集聚进行了结构和行业的细分,结构上分为专业化集聚、多样化集聚与城市经济规模集聚,行业上分为工业与服务业两种产业的集聚。研究发现,服务业的专业化和多样化集聚与城市经济增长都存在显著的U形关系,说明这两种集聚带来的拥塞效应快于对经济的促进作用,并且,我们以就业密度为指标计算U型拐点是665人/Km2。而工业集聚中无显著的非线性关系,城市经济规模变量与经济增长之间一直存在着稳定的倒U形关系。     

房价对城市全要素生产率的影响机制研究——基于Tobit模型实证分析

基于2008—2016年全国35个大中型城市的面板数据,利用Tobit模型和投入导向型的数据包络分析(DEA)方法探究城市房屋销售价格对城市全要素生产率的影响。研究发现：在整体维度城市房价与城市生产率呈现先增加后减少的倒U型曲线,且城市的房价水平超过了“房住不炒”的最高临界值,房价上升的抑制效应显著。房价对于不同人口规模城市的生产率影响具有异质性,在人口规模达到特大城市时,房价与城市生产率呈现倒U型特征,人口规模达到超大城市后,房价与城市生产率倒U型特征消失。不同类型城市房价与城市生产率之间的倒U型关系和城市的异质性特征表明,我国大中型城市应进行房价的“一城一策”精细化调节,“房住不炒”的政策定位具有坚实理论依据和现实必然。     

城市规模、空间集聚与电力强度

中国仍处在快速城市化的过程中,城市人口、工业及其他因素共同决定着不同的城市规模和产业结构,进而影响着一个城市的电力强度水平。本文选取了2003—2013年我国31个省级行政区267个地级市相关数据,通过建立动态面板模型进行回归分析。研究结果表明,城市规模与电力强度之间存在倒U型的非线性关系,即随着城市规模的扩大电力强度出现先上升后下降的现象。为了进一步探索城市规模对电力强度的影响机制,本文引入空间集聚的概念,同时构建了一个用来反映省级行政区内部空间集聚水平的重要指标——空间基尼系数。本文利用相关数据对空间基尼系数进行计算,并将其纳入模型进行回归分析。研究结果发现,空间集聚对电力强度确实具有一定程度的负向影响。本文研究结论从优化电力强度的视角,探讨了城市电力强度最优条件下的合理城市规模,并为我国城市化过程中建设现代化的大型城市提供了实践参考与决策支持。     

产业集聚、公共服务供给与城市规模扩张

本文基于中国工业企业数据和城市面板数据,从产业集聚和公共服务供给的综合视角探讨了城市人口规模扩张的影响机制。结果显示,专业化集聚和多样化集聚均有助于提高本市人口规模,但对周边城市却产生了负向空间外溢效应,且专业化集聚的作用效果明显大于多样化集聚;公共服务供给不仅提高了本市和周边城市人口规模,而且能够在城市人口增长中与产业集聚形成协同效应。进一步研究发现,民生类公共服务对城市人口规模增长的作用效果明显大于基础设施类公共服务,且产业集聚模式越符合当地优势条件,其集聚效应和空间外溢效应发挥得就越充分。其中,专业化集聚主要基于第一自然集聚优势、劳动力蓄水池效应和制造业中间投入的空间共享机制而发挥作用,而多样化集聚则主要基于中间服务的空间共享机制和空间技术外溢效应而产生影响。在适宜性产业集聚和公共服务供给的双重作用下,多数Ⅰ型及以上大城市拥挤效应得到明显缓解,依然具有很强的人口吸纳能力;Ⅱ型大城市和中小城市的产业集聚模式与城市规模特征更为匹配,有助于扭转结构错配、持续推进人口城市化。     

经济集聚对绿色经济效率的影响

经济集聚是指经济活动在某一地理区域内相对集中的现象.绿色经济效率是在现有全要素生产率分析框架下,将能源消耗纳入投入变量并考虑环境污染作为非期望产出测算出的社会经济运行效率.在现有经济集聚对经济增长的研究基础上,重点研究能源消耗和环境污染的负面效应与经济增长脱钩后经济集聚对低污染、高能效的绿色经济效率的影响,完善了经济集聚对绿色经济的影响研究.文章构建了在经济集聚的不同阶段通过规模效应、技术效应、产品产业结构效应和政策环境效应对绿色经济效率的影响存在"U"型曲线关系的理论分析框架.采用2004-2017年中国29个省级行政区(省、自治区、直辖市)的面板数据进行空间计量实证检验.结果表明,经济集聚和绿色经济效率之间呈现出"先降低-后升高"的"U"型曲线关系,并通过工具变量对内生性问题做了进一步处理,体现了模型良好的稳定性.     

通达性与城市空间效率:基于要素集聚的视角

基于2009—2020年中国282个地级以上城市的面板数据,分析了通达性的改善对我国城市空间效率影响及作用机制。研究发现:(1)通达性的改善能够促进城市空间效率提升,且可以有效吸引劳动力与资本的集聚,促进城市土地要素的有效利用;(2)城市通达性对城市空间效率的直接促进作用大于通过要素集聚作用于城市空间效率的间接促进作用;(3)分城市规模和经济禀赋来看,城市通达性的变化对大规模城市和贫困地区城市的城市空间效率影响程度分别大于对中小规模城市和非贫困地区城市的影响程度。因此,加快交通基础设施建设,促进城市间互联互通,激发要素集聚的中介效应,将有助于中国城市高效率发展。     

长三角地区高技术产业集聚的环境污染效应

利用长三角地区2006—2018年的城市面板数据,以区位熵指数测算高技术产业集聚水平,运用熵权法测算环境污染程度。构建扩展的STIRPAT模型并运用广义最小二乘法(GLS)进行实证检验。结果表明:高技术产业集聚对环境污染的影响存在倒"U"型效应,上海、江苏以及2006—2010年的浙江都处于倒"U"型曲线的右侧,即高技术产业集聚水平的提升改善环境污染;安徽以及2010—2018年的浙江处于倒"U"型曲线的左侧,即高技术产业集聚水平的提高加剧环境污染。另外,长三角地区的人口规模、经济发展水平、环境规制强度和产业结构对环境具有负外部性;高技术产业集聚与技术水平的交叉项以及技术水平对环境具有正外部性。     

产业发展从人口集聚中受益了吗?——基于2005-2011年城市面板数据的经验研究

本文利用2005-2011年中国地级及以上城市的面板数据,使用统计分析和工具变量回归,研究了近些年中国城市人口集聚对第二产业、第三产业以及非农产业劳动生产率的作用,并且进一步分析了不同人口规模城市受集聚经济的不同影响。结果表明,人口集聚效应总体上对非农劳动生产率有显著促进作用,但对第二产业的劳动生产率的影响并不明显,甚至为负值,第三产业则享受了更多集聚经济的好处;人口集聚并非越强越好,人口规模超过某个水平反而会抑制劳动生产率;不同规模城市的集聚效应略有差别,中小城市对集聚的好处更加敏感。     

产业集聚与城市生态效率动态关系研究

基于2004-2016年285个城市面板数据,运用静态面板、动态面板及面板门槛模型,从整体趋势、时间效应及非线性结构3个方面分析不同产业集聚模式差异与城市生态效率间的动态关系。结果显示,生产性服务业尤其是高端生产性服务的专业化及多样化集聚会在短期抑制生态效率提升,但长期促进作用显著;生产性服务业与制造业协同集聚对生态效率的改进效果相比单一产业集聚更为显著;不同产业集聚模式对生态效率的作用存在门槛效应,两者之间呈现显著倒U型关系,且存在集聚最优值;城市规模对产业集聚与城市生态效率的关系呈负向调节作用。因此,在城市生态经济规划建设中,应加大高端生产性服务业建设投入力度,关注生产性服务业与制造业融合,根据城市基础条件制定相应的产业转移战略,且不可集聚过度,注重发挥产业集聚对城市生态建设的正向促进作用。     

Growth and Agglomeration

This article presents a model in which growth and geographic agglomeration of economic activities are mutually self-reinforcing processes. Economic agglomeration in one region spurs growth because it reduces the cost of innovation in that region through a pecuniary externality due to transaction costs. Growth fosters agglomeration because, as the sector at the origin of innovation expands, new firms tend to locate close to this sector. Agglomeration implies that all innovation and most production activities take place in the core region. However, as new firms are continuously created in the core, some relocate their production to the periphery.     

Agglomeration and fair wages

Abstract.  This paper implements a fair wage constraint into an analytically tractable core-periphery agglomeration model. This enables us to study the role of imperfect labour markets for the pattern of agglomeration. In the short run, a marginal increase in fair wage preferences leads to an unambiguous compression of the national factor price differential between skilled and unskilled labour, involving an increase in the unemployment rate of unskilled workers. In the long run, this mechanism renders full dispersion of an unstable equilibrium already at higher trade costs than in perfect labour markets. There is a tendency for fair wage preferences to enforce agglomeration.     

Agglomeration and Firm Export

Using Chinese manufacturing data between 1998 and 2007, this paper investigates the impact of agglomeration on firm’s export behavior. It is found that the agglomeration of manufacturing industries in China over this period increases firm’s export probability as well as its export volume, and the impact is larger for more efficient firms. However, the impact on firm’s export volume depends on the degree of agglomeration. When the degree of agglomeration is low, an increase in agglomeration would expand firm’s export volume but the impact will be diminishing and even turns negative if the degree of agglomeration is already very high.     

Agglomeration and tax competition

Tax competition may be different in ‘new economic geography settings’ compared to standard tax competition models. If the mobile factor is completely agglomerated in one region, it earns an agglomeration rent which can be taxed. Closer integration first results in a ‘race to the top’ in taxes before leading to a ‘race to the bottom’. We reexamine these issues in a model that produces stable equilibria with partial agglomeration in addition to the core-periphery equilibria. A bell-shaped tax differential also arises in our model. Therefore, the ‘race to the top’ result generalises to a framework with partial agglomeration.     

On Mergers and Agglomeration

We formulate a model of mergers and acquisitions assuming a monopolistic competitive industry that exhibits agglomeration economies. We provide the conditions for the existence of a non‐trivial Nash equilibrium in the acquisition market at which the most productive firm acquires a range of less‐productive firms. Most importantly, we show that domestic merger and acquisition activities are international trade promotionary. We also show that such types of mergers and acquisition will improve the competitive position of foreign firms leading to an increase in their market share. In addition, domestic mergers and acquisitions will increase the number of imported varieties.     

Agglomeration effects in Europe

The paper estimates agglomeration effects for France, Germany, Italy, Spain, and the UK. Estimation takes into account endogeneity of the spatial distribution of employment and spatial fixed effects. Empirical results suggest that agglomeration effects in these European countries are only slightly smaller than agglomeration effects in the US: the estimated elasticity of (average) labor productivity with respect to employment density is 4.5 percent compared to 5 percent in the US.     

Agglomeration in a vertically-related oligopoly

This paper examines the location of three vertically-linked firms. In a spatial economy composed of two regions, a monopolist firm supplies an input to two consumer goods firms that compete in quantities. It is concluded that agglomeration is more likely to occur when the ratio between the transport cost of the intermediate good and the transport cost of the final good is higher. If this proportion is low, the likelihood of an agglomeration decreases with transport costs. If the ratio has an intermediate value, a non-monotonic pattern is obtained that is different from Krugman and Venables (1995).Received: October 2004, Accepted: March 2005, JEL Classification: C68, F12, F15, R12, R13This paper had the support of the Research Unit on Complexity in Economics (UECE). The author wishes to thank Masahisa Fujita, Armando Pires and an anonymous referee for helpful comments. The usual disclaimer applies.     

Interregional Fertility Differentials and Agglomeration

In this study, we construct an interregional trade model that includes endogenous fertility rates. The presented model shows that the agglomeration of manufacturing firms in a large region causes fertility rates to become lower than in a small region. We also find that a decrease in transportation costs results in the agglomeration of manufacturing firms, which lowers fertility rates in both large and small regions. In addition, comparing the competitive equilibrium with the optimal equilibrium, the fertility rates may be inefficiently small.