Intranational Home Bias in Trade
基于引力模型，研究发现美国各州内部也存在本土偏好，表明除了贸易壁垒外，还有其他因素导致国内贸易过度。
A number of recent studies have found intranational trade to be excessive compared to international trade, based on a gravity specification. The preferred explanation for this finding has been the presence of formal and informal trade barriers, with associated welfare consequences. If such barriers were indeed the sole culprit, home bias should not exist on the subnational level. We find, however, that home bias is present within U.S. states, suggesting the presence of other causes of excessive home trade. © 2000 by the President and Fellows of Harvard College and the Massachusetts Institute of Technology