IV regression with distribution-valued outcomes
分布值结果的IV回归
David Van Dijcke, Kaspar Wüthrich
AI总结 提出IV Fréchet回归(IVFR),一种针对结果为整个分布的工具变量方法,通过2-Wasserstein空间中的IV回归扩展全局Fréchet回归以处理内生协变量,并证明投影减少估计误差、保证有效拟合分布,且估计量弱收敛到高斯过程。
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- 37 pages, 4 figures, 2 tables
我们开发了IV Fréchet回归(IVFR),这是一种工具变量(IV)方法,适用于结果为整个分布的情况。将问题表述为2-Wasserstein空间中的IV回归,IVFR将全局Fréchet回归扩展到存在内生协变量的情况。IVFR将IV加权分位曲线投影到有效分布空间上,然后恢复相应的回归系数函数。该投影可证明地减少有限样本中的估计误差,并保证有效的拟合分布。我们证明了IVFR估计量弱收敛到均值为零的高斯过程,并建立了用于均匀推断的乘子自助法的有效性。在模拟中,与现有方法相比,投影将积分均方误差(IMSE)降低了高达63%。重新审视中国进口竞争对通勤区内工资分布的影响,所提出的方法产生的置信带比现有方法窄9-10%。使用我们新颖的均匀置信带,我们没有发现进口竞争降低了分布最底端工资的证据,但发现在第10至第35百分位数之间有影响。我们还重新审视了县级食品券计划对县出生体重分布的影响,并未发现显著影响。
We develop IV Fréchet regression (IVFR), an instrumental-variable (IV) method for settings where the outcome is an entire distribution. Framing the problem as an IV regression in 2-Wasserstein space, IVFR extends global Fréchet regression to the case with endogenous covariates. IVFR projects IV-weighted quantile curves onto the space of valid distributions and then recovers the corresponding regression coefficient functions. The projection provably reduces the estimation error in finite samples and guarantees valid fitted distributions. We show that the IVFR estimator converges weakly to a mean-zero Gaussian process and establish the validity of a multiplier bootstrap procedure for uniform inference. In simulations, the projection reduces the integrated mean squared error (IMSE) by up to 63% relative to existing methods. Revisiting the effects of Chinese import competition on the wage distribution within commuting zones, the proposed method produces 9-10% narrower confidence bands than existing methods. Using our novel uniform confidence bands, we find no evidence that import competition reduced wages at the very bottom of the distribution, but only between the 10th and 35th quantile. We also revisit the effect of county food stamp programs on the county's birth weight distribution and find no significant effects.