Estimating gravity equations for trade in value added: A structural perspective
通过理论和模拟证明，当传统贸易引力方程正确时，增加值贸易引力方程存在设定错误，导致估计结果难以解释且易遗漏变量偏差，对使用增加值数据的研究者具有警示意义。
A large number of recent papers employ value-added trade data alongside traditional gross measures of trade to estimate the impact of various trade costs on bilateral trade. Value-added gravity equations are typically justified by referencing the theoretical and empirical merits of traditional gravity equations for gross trade. Contradicting this notion, we use theory and simulations to show that value-added gravity equations are misspecified when the gross trade gravity equation is correct. Consequently, estimates from value-added gravity equations are difficult to interpret and prone to omitted variables bias.