We estimate a gravity model for 205 countries, with data from 1954 to 2014, allowing for multiple layers of heterogeneity. The first layer arises from the interactions between a set of traditional gravity variables. The second one comes from country pairs that differ in values of the binary time-independent gravity variables. Further layers come from different income groups and regions. Our results show the importance of heterogeneities at various levels. For instance, landlockedness is less restrictive when trading partners are contiguous or colonially linked. We also find, for example, that the positive interaction between landlockedness and contiguity is more (less) pronounced when non-high-income countries import (export) or when Middle East and North Africa (MENA) countries import, and the negative interaction between landlockedness and language similarities is stronger when MENA countries export.

中文翻译：

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估计具有多层异质性的重力系数


我们利用 1954 年至 2014 年的数据估算了 205 个国家的引力模型，考虑到多层异质性。第一层由一组传统重力变量之间的相互作用产生。第二个来自与时间无关的二元重力变量值不同的国家对。更多层次来自不同收入群体和地区。我们的结果显示了不同层面上异质性的重要性。例如，当贸易伙伴毗邻或有殖民地联系时，内陆的限制性较小。例如，我们还发现，当非高收入国家进口（出口）或中东和北非（MENA）国家进口时，内陆性与毗连性之间的正向相互作用更加（不那么）明显，而当非高收入国家进口（出口）或中东和北非（MENA）国家进口时，内陆性与毗连性之间的负向相互作用更加（不那么）明显。当中东和北非国家出口时，内陆性和语言相似性更强。