关键词: 港口整合, 合成控制法, 复合中介效应模型, 作用机制, 集装箱吞吐量

Abstract: Ports have been traditionally recognized as important catalysts in both urban and regional economic development. Thus, most coastal cities have made substantial investment in their local port gateways to expand port capacity and increase port service level in order to achieve the goal of “port prospering the city”. However, problems caused by the great enthusiasm in developing the local ports of port cities under “one city one port” governance mode gradually have come to light, such as the over-exploitation of coastal resources, the inefficiency utilization of port resources, and the disorder of port market competition. To address the issues of cut-throat inter-port competition and the wasting port resources, the Ministry of Transport (MOT) of China issued the “guideline for promoting the transformation and upgrading of ports” in 2014 and “regional port integration pilot program” again in 2015, leading to the port integration of “one province, one port” mode being the mainstream trend of China's regional port reform and upgrading at present. In this context, evaluating the effectiveness of the provincial port integration and exploring how it would affect the provincial port cluster are of critical importance, not only to the adjustment and deepening of regional port integration and reform policies, but also to the improvement of the economic effect of port integration.
As Zhejiang is a pioneer in provincial port integration (PPI), this paper utilizes synthetic control method (SCM) to quantitatively evaluate the effect of PPI on the development of container port throughput (PCT), with 9 other provinces which have not implemented regional port integration from 2004 to 2018 as the control groups. The reason why SCM is adopted is that it avoids the subjective selectivity bias and does not depend on the presence of parallel trends compared with the methods of Difference-in-Difference (DID) and Propensity Score Matching (PSM) which are widely used in literatures related to policy evaluation, and SCM seems more empirically feasible to investigate whether the partial growth of PCT is caused by the implementation of PPI under the context of PCT showing a general upward trend in China. On the basis of SCM analysis, in-time and in-space placebo tests are performed to verify the validity and robustness of the synthetic results. Further, based on the PCT data and other port development related data of 16 administrative provincial regions with container port distribution spanning 2004—2020, the mediation effect model consisting of both parallel and serial mediations is constructed to explore the transmission mechanism by which the PPI affects port development within the province.
The results show that the PPI has led to a significant improvement of port container throughput volume within Zhejiang. The synthetic results pass both in-time and in-space placebo tests, indicating that the increase in port container throughput is related to provincial port integration instead of other events and the results are robust on the condition of making changes to the time of provincial port implementation in the research design. The exploration of the mechanism of the implementation effect shows that PPI has an indirect positive impact on the development of container ports mainly through the compound mediating effect of port efficiency improvement as the first stage mediator, foreign trade increase and industrial structure optimization, two factors as the second stage parallel mediators. However, PPI has no significant direct effect on port container throughput. The main contributions of this study are threefold. First, it is the first to investigate the impact of PPI on the provincial port cluster, which has provided the evidence for the increase in PCT because of a shift of port governance mode from “one city one port” to “one province one port”. Second, the SCM is innovatively used in the port integration study, which can fully capture unobserved time-varying confounders and overcome multiple biases of the traditional estimation model. Third, the mechanism of PPI function on the development of the provincial port cluster is explored.
However, this study still has some limitations, for instance, only the PCT data as the indicator of port development is used, without considering other factors such as revenue and profitability of the provincial port group. Moreover, the average or total impact of PPI on other provinces that have undergone regional port consolidations that cross administrative barriers in China has not been discussed. If data permit, we would carry out in-depth research along the above two directions in the future.

Key words: port integration, synthetic control method, compound mediation effect model, function mechanism, container throughput