虹吸与溢出：科技和金融结合试点政策的空间效应
孟溦，高鸿怡
（华东师范大学 公共管理学院，上海200062）
摘要：基于2002—2020年265个城市的面板数据，采用空间双重差分（SDID）重新检验了试点政策的效果并识别其空间效应表现为虹吸还是溢出。研究发现：（1）在考虑空间效应的前提下，试点政策对试点城市科技创新水平的提升作用仍然显著；（2）试点政策整体上具有空间溢出效应，促进了非试点城市科技创新水平提升；（3）试点政策的空间效应在同一省级政府辖区内同级地方政府间表现为溢出，促进了省内创新共享，但空间效应在跨越省界后表现为虹吸。稳健性检验支持本文结论。本文表明新经济地理（NEG）理论所强调的中心城市对周边城市的虹吸效应和溢出效应同时存在，其相对大小决定政策空间效应的形态。因此政府在推动试点政策有序扩散的同时，必须兼顾地区间利益分配关系，保证政策效果在跨省级行政区划间的连续性，促进区域协同创新。本文为中央纵向干预地方政府协作行为，突破区域束缚打造统一大市场提供了理论依据。
关键词：科技金融；科技创新；政策评估；空间双重差分
主要研究结论：从“科技就是第一生产力”到“创新是引领发展的第一动力”，科技创新能力已然成为综合国力竞争的决定性因素。准确评估促进科技和金融结合试点政策的“试点价值”和“示范价值”，对于完善科技金融支撑科技创新的制度安排、建设创新型国家具有重要意义。本文利用2002至2020年265个城市的面板数据，从空间效应的角度，采用SDID分析试点政策对城市科技创新水平的影响，并进行了稳健性检验。我们得出以下主要结论：
（1）在政策评估方法层面。本文的研究结果揭示了已有研究忽略空间效应存在的双重差分估计是有偏的，将会高估政策效果。
（2）在试点政策评估层面。研究发现，在考虑空间效应的前提下，促进科技和金融结合试点政策在促进试点城市科技创新水平提升的同时，也整体上促进了非试点城市科技创新。空间效应的存在实证验证并丰富了中国政策试点的内生价值，也为提升事后政策评估的科学性做出了理论贡献。
（3）在理论对话层面。本文验证了新经济地理（NEG）理论所强调的中心城市对周边城市的虹吸效应和溢出效应同时存在，而试点政策的总效应之所以在省界处呈现出差异，其实是这两种力量相互作用的结果。当虹吸效应大于溢出效应时，整体上虹吸效应占主导，政策试点将会抑制非试点城市科技创新。当溢出效应大于虹吸效应时，整体上溢出效应占主导，政策试点能够促进非试点城市科技创新。
（4）在政策过程理论层面。试点政策的空间效应在同一省级政府辖区内表现为溢出效应，在非同一省级政府辖区表现为虹吸效应。研究发现的两种异质性空间效应一定程度上超出了政策设计之初的预期，进而拓展了政策反馈在政策评估中的研究，为后续研究试点政策创新扩散中的地方政府竞争与学习做出了贡献。
Siphons and spillovers: The spatial effects of the pilot policies for combining technology with finance
Meng Wei, Gao Hongyi
(School of Public Administration, East China Normal University, Shanghai 200062, China)
Abstract:As a place-based intervention experiment, policy makers not only expect the pilot policy for combining technology with finance to play a "pilot role" to enhance the independent innovation capability of pilot areas, but also pay more attention to its "promotion value" and whether it can play a demonstration role to drive the integration of science and technology and finance in more regions and accelerate independent innovation. PSM-DID method has been used to evaluate the "pilot role" of the pilot policy for combining technology with finance comprehensively, but its spatial effect in non-pilot cities has not been carefully investigated. The study of the spatial effect of the pilot policy for combining technology with finance is related to its further promotion and practice, which is an important clue to understand the development of regional science and technology innovation. In particular, how does this spatial effect manifest itself? Siphon or spillover? It is controversial.
Based on the panel data of 265 cities from 2002 to 2020, this paper takes the "pilot policy for combining technology with finance" promulgated and implemented by the Ministry of Science and Technology in conjunction with the People′s Bank of China, the China Banking Regulatory Commission, the China Securities Regulatory Commission and the China Insurance Regulatory Commission in 2011 and 2016 as a quasi-natural experiment. For the first time, spatial difference-in-differences (SDID) analysis was used to quantitatively estimate its spatial effect on non-pilot cities.
The findings are as follows: (1) Under the premise of considering the spatial effect, the effect of the pilot policy on improving the level of technological innovation in pilot cities is still significant; (2) The pilot policy have spatial spillover effect on the whole, which promotes the scientific and technological innovation level of non-pilot cities; (3) The spatial effect of pilot policies is spillover between local governments at the same level within the same provincial government jurisdiction, which promotes innovation sharing within the province, but the spatial effect is siphon after crossing provincial boundaries, which is not conducive to the scientific and technological innovation of non-pilot cities in different provincial-level regions Robustness test and placebo test both supported the conclusions of this paper.
This study empirically tests the spatial effect of the pilot policy for combining technology with finance, and further confirms that the SUTVA hypothesis in the difference-in-differences method is not valid. Ignoring the spatial effect of the pilot policy for combining technology with finance will produce deviation in policy evaluation. The existence of spatial effect has verified and enriched the value of China′s policy pilot and made theoretical contribution to improving the scientific nature of policy evaluation after the event. The heterogeneity of the spatial effects of pilot policies on provincial administrative boundaries is also found, which fills the gap of previous studies.
This paper shows that the siphon effect and spillover effect of the central city on the surrounding city emphasized by the New Economic Geography (NEG) theory exist simultaneously, and the relative size determines the shape of the spatial effect of policy. When the siphon effect is greater than the spillover effect, the overall siphon effect dominates, and the policy pilot will inhibit the technological innovation of non-pilot cities. When the spillover effect is greater than the siphon effect, the spillover effect dominates on the whole, and the policy pilot can promote the technological innovation of non-pilot cities. Therefore, in order to accelerate the realization of the innovation-driven development strategy, the government must fully consider the inter-regional interest distribution relationship while promoting the orderly diffusion of pilot policies, pay attention to the influence of the internal political process and administrative structure of local governments on policy innovation and diffusion, and ensure the continuity of policy effects across provincial administrative divisions.
This finding further provides theoretical support for the central government to intervene vertically in the cooperative behavior of local governments, break down local protectionism, crack market segmentation and break through regional constraints to build a unified large market. To build bridges for innovation sharing, promote knowledge flow across administrative regions, and promote regional collaborative innovation.
Key words:science and technology finance; scientific and technological innovation; policy assessment; spatial difference-in-differences (DID) method
引用本文：孟溦,高鸿怡.虹吸与溢出：科技和金融结合试点政策的空间效应[J].科研管理,2023,44(6):62-73.
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