The increasing policy interests and the vivid academic debate on non-tariff measures (NTMs) has stimulated a growing literature on how NTMs affect agrifood trade. The empirical literature provides contrasting and heterogeneous evidence, with some studies supporting the standards as catalysts view, and others favouring the standards as barriers explanation. To the extent that NTMs can influence trade, understanding the prevailing effect, and the motivations behind one effect or the other, is a pressing issue. We review a large body of empirical evidence on the effect of NTMs on agri-food trade and conduct a meta-analysis to disentangle potential determinants of heterogeneity in estimates. Our findings show the role played by the publication process and by study-specific assumptions. Some characteristics of the studies are correlated with positive significant estimates, others covary with negative significant estimates. Overall, we found that the effects of NTMs vary across types of NTMs, proxy for NTMs, and levels of details of studies. Not negligible is the influence of methodological issues and publication process.

中文翻译：

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非关税措施对农产品贸易的影响：实证研究的回顾与荟萃分析

越来越多的政策兴趣和关于非关税措施（NTM）的激烈学术辩论，激发了有关NTM如何影响农产品贸易的文献。经验文献提供了相反和不同的证据，一些研究支持标准作为催化剂的观点，而另一些研究则支持标准作为障碍的解释。就NTM可以影响贸易的程度而言，了解主要影响以及一种影响或另一种影响的动机是一个紧迫的问题。我们回顾了大量关于NTM对农业食品贸易影响的经验证据，并进行了荟萃分析，以消除估计中异质性的潜在决定因素。我们的发现表明了出版过程和特定研究假设所起的作用。研究的某些特征与阳性显着估计相关，其他特征与阴性显着估计相关。总体而言，我们发现NTM的效果随NTM的类型，NTM的代理以及研究细节水平的不同而不同。方法学问题和出版过程的影响不可忽略。