Nonparametric bounds on the returns to language skills
运用非参数处理效应边界理论，估计有限英语能力对美国西班牙裔工人工资和就业机会的影响，发现两个弱假设结合可为特定人群提供语言技能回报的上界，加入到达年龄作为单调工具变量可提供下界。
Abstract This paper applies the theoretical literature on nonparametric bounds on treatment effects to the estimation of how limited English proficiency (LEP) affects wages and employment opportunities for Hispanic workers in the United States. I analyse the identifying power of several weak assumptions on treatment response and selection, and stress the interactions between LEP and education, occupation and immigration status. I show that the combination of two weak but credible assumptions provides informative upper bounds on the returns to language skills for certain subgroups of the population. Adding age at arrival as a monotone instrumental variable also provides informative lower bounds. Copyright © 2005 John Wiley & Sons, Ltd.