New Trade Models, New Welfare Implications
证明内生企业选择为异质性企业贸易模型提供了新的福利维度，并指出在一般设定下，国内贸易份额和内生贸易弹性不再是福利的充分统计量，微观结构的其他可观测特征也影响福利。
We show that endogenous firm selection provides a new welfare margin for heterogeneous firm models of trade (relative to homo geneous firm models). Under some parameter restrictions, the trade elasticity is constant and is a sufficient statistic for welfare, along with the domestic trade share. However, even small deviations from these restrictions imply that trade elasticities are variable and differ across markets and levels of trade costs. In this more general setting, the domestic trade share and endogenous trade elasticity are no longer sufficient statistics for welfare. Additional empirically observable moments of the micro structure also matter for welfare.