SPS措施对农产品贸易的影响——基于Heckman两阶段方法的实证分析

1.华东理工大学 商学院, 上海 200237
2.上海大学 经济学院, 上海 200444

[作者简介] 1.董银果(http://orcid.org/0000-0003-0359-8223),女,华东理工大学商学院教授,博士生导师,管理学博士,主要从事SPS和农产品贸易研究; 2.李圳(0000-0002-8700-8296),男,上海大学经济学院应用经济学硕士研究生,主要从事SPS和农产品贸易研究。

SPS措施是WTO框架下农产品贸易的主要非关税措施。进口国设立SPS作为一种产品质量门槛,其遵从成本首先影响企业的市场进入行为,进而影响其贸易流量。发达国家的出口企业在资金、人才、技术和供应链系统方面更具有遵从的优势,贸易可能由发展中国家转向发达国家。对SPS措施贸易偏转效应的实证检验发现,在SPS措施实施的第一和第二年,贸易偏转效应不明显,原因在于SPS协议对发展中国家有区别对待原则,且农产品生产的区域特征明显。但在SPS措施实施的第三和第四年,农产品进口来源由发展中国家转向发达国家,存在贸易偏转效应。作为农产品出口国,这要求中国的出口企业提高技术水平,增加农产品产业链的固定投资,以遵从国外SPS措施为契机,提高农产品质量层次。

Effects of SPS Measures on Agricultural Products Trade: An Empirical Analysis Based on Heckman’s Two-step Method
Dong Yinguo1, Li Zhen2
1.School of Business, East China University of Science and Technology, Shanghai 200237, China
2.College of Economics, Shanghai University, Shanghai 200444, China
Abstract

Sanitary and phytosanitary (SPS) measures are the main non-tariff measures for the trade of agricultural products under the framework of WTO. The importing countries set SPS measures, based on the consideration of preventing risks, protecting consumers, and protecting plants and ecological environment from being damaged by the exotic pathogens, biology and insect pest carried by agricultural products. However, SPS measures can easily be overused as trade barriers restricting foreign products. Therefore, the impact of SPS measures on the export of agricultural products has been the focus of scholars’ research, but there has been scant research on the impact of the same SPS measures on the country of different levels of development. In fact, as a product quality threshold, the compliance cost of SPS first affects an enterprise’s market entry behavior, followed by the impact of trade flow, i.e. SPS measures affect the binary boundary, the breadth and the depth of agricultural products. Confronting the SPS measures of importing countries, especially developed countries, the export enterprises of developed countries have more compliance advantages than those of developing countries in terms of capital, talent, technology and supply chain system. Trade may divert from developing countries to developed countries. The trade diversion effect in theory has not been verified in empirical analysis yet.

Based on the firm heterogeneity assumptions of new-new trade theory, this paper analyzes the difference impact of SPS measures on heterogeneous firms, and then empirically test the trade diversion effect of SPS measures by adopting China’s import trade data of agricultural products (HS01-24) between 1995 and 2013, and the data from such developed countries as EU, Australia, Japan, the United States, and Canada, and by employing the Heckman’s two-step method. It has found out that in the first and second years when SPS measures are implemented, trade diversion effect is ambiguous because of the principles of differential treatment for developing countries in SPS agreement, and the resource endowment of agricultural production. However, in the third and fourth years of implementation, the import source of agricultural products from developing countries switches to developed countries. Based on the weaknesses of developing countries in the SPS measures, international organizations such as the standard and trade development facilities have been helping the traditional industries in developing countries since 2004 to adapt to the SPS measures of developed countries.
The trade diversion effect of SPS measures will be beneficial to China, the world’s largest importer of agricultural products, who can increase import quality and safety level of agricultural products by implementing SPS measures. But this will challenge China as an exporter of agricultural products as it requires China’s export enterprises to take the opportunity of complying with the foreign SPS measures to improve product quality by upgrading their technological level and increasing the fixed investment in the industrial chain of agricultural products.

Keyword: sanitary and phytosanitary(SPS) measures; agricultural products trade; import; trade diversion effect; Heckman’s two-step method

SPS协议制定的初衷是规范各国对SPS措施的使用, 使SPS措施在农产品市场开放后能充分发挥其保护人类食品安全、动植物健康以及环境安全的作用, 而不至于成为新的非关税壁垒, 从而阻碍全球贸易的发展。然而, SPS措施的特性决定了其既有保护本国消费者和生产者免受进口产品携带的外部风险损害的功能, 同时也会因过度使用而产生贸易限制作用, 两者的界限较为模糊, 很难区分[1]。因此, SPS措施的贸易效应一直是学界关注的焦点。

Melitz率先打破企业同质性假设, 将企业生产率的异质性纳入分析框架, 分析贸易自由化带来的影响[16], 进而出现了异质性企业贸易理论。企业生产率的差异在宏观层面上表现为国家间生产率的差异。但由于其模型忽视了产品质量因素, 造成与相关实证研究不符[17]。此后的许多研究引入产品质量异质性对Melitz的模型进行扩展, 以生产效率和产品质量双重异质性为切入点, 重新剖析微观企业的出口行为选择[18]。Hallak和Sivadasan认为, 当存在最低出口产品质量要求时, 生产率已不再是决定企业能否出口的唯一条件, 生产率很高但产品质量很低的企业亦无法出口; 给定生产率水平时, 企业固定投入效率越高, 产品质量越高, 企业就越容易进入出口市场[19]

(一) 传统引力模型的缺陷

(二) 模型和变量介绍

Probit(Dummyijst)=β 01importdaysijs2importcostijs3ln(GNIit)4ln(GNIjst)5ln(Dijs)6Contigijs7Colonyijs8Comlangijs9RTAijst10Developedijst+ $∑n=1$(β sd, nSDijs, t-nsps, nSPSijs, t-n)+xi+xj+yeart (1)

Shareijst01ln(GNIit)2ln(GNIjst)3ln(Dijs)4Contigijs5Colonyijs6Comlangijs7RTAijt8Developedijst+ $∑n=1$(β sd, nSDijs, t-nsps, nSPSijs, t-n)+xi+xj+yeart+ln{exp[δ s(zijst+IMRijst)-1]}IMRijst+uijst (2)

ln{exp[δ s(zijst+IMRijst)-1]}用来捕捉异质性出口商的出口贸易效应。其中, 较大的δ 表示出口商异质性程度较强, 即较多的潜在出口商和较少的实际出口商。zijst是模型(2)的线性估计值, IMRijst是逆米尔斯比, 模型(1)计算出的标准样本选择误差控制项。模型(1)和(2)中其他解释变量, 如GNIit、GNIjstDijs、Contigijs、Colonyijs、Comlangijs、RTAijt以及SPSijst, 其含义及预期符号见表1

xixj、year分别为进口国固定效应、出口国固定效应、年份固定效应, 由于样本数量的限制, 在自变量层面有较大的变动, 因而用出口国、进口国、时间固定效应来代替“ 出口国— 进口国— 时间” 固定效应[27]

(三) 数据

SPS措施是由进口国设立的以保护人类健康、食品安全、动植物健康与生态环境安全等为目的的法律、法规、要求和程序, 会同时对供给(出口国、出口企业)和需求(进口国消费者)产生影响。各个国家农产品生产技术水平不同, 受SPS措施的影响也不同。农产品生产企业由于生产效率和产品质量的异质性, 对进口国SPS措施的反应时间也有长短之别。反映在国家层面, 发达国家出口国在面临新的SPS措施时, 凭借技术和资本优势, 可以更快地调整以适应进口国的SPS措施对产品质量的要求; 而发展中国家由于在技术和资本上的劣势, 需要更长的时间来适应, 甚至会出现无法满足要求而退出市场的状况。因此, SPS措施的实施会导致农产品进口从发展中国家转向发达国家, 即贸易偏转效应。本文基于主要农产品贸易国的数据, 采用Heckman两阶段方法的研究表明, SPS措施在执行的第一和第二年, 贸易偏转效应不明显, 而SPS措施在实施的第三到第四年, 农产品贸易的格局发生变化, 贸易由发展中国家转向发达国家。

The authors have declared that no competing interests exist.