Lutian Zhao UID: 661622198 The Duistermaat-Heckman theorems concern the measure associated to moment map of a torus action of symplectic manifold. Typically, this name refers to two theorems, one is called the ”Duistermaat-Heckman measure", which says that ”the Radon-Nikodym derivative is piecewise polynomial", the definition of each terms will be introduced later. The second one is called ”Dui...

This article describes qregsel, a Stata module to implement copula-based sample selection correction for quantile regression recently proposed by Arellano and Bonhomme (2017, Econometrica 85(1): 1-28). The command allows the user model in regressions using either Gaussian or an one-dimensional Frank copula. We illustrate use of qregsel with two examples. First, we apply method fictional data se...

Heckman advocates an approach to causal inference that draws upon structural modeling of the outcome(s) of interest (which he calls scientific), and he contrasts this approach sharply with that arising out of the statistical literature on experimentation. Drawing extensively on several previous papers—for example, Heckman (1997, 2000, 2001) and Heckman and Navarro-Lozano (2004)—Heckman goes eve...

In the social sciences, evaluating the effectiveness of a program or intervention often leads researchers to draw causal inferences from observational research designs. Bias in estimated causal effects becomes an obvious problem in such settings. This article presents the Heckman Model as an approach sometimes applied to observational data for the purpose of estimating an unbiased causal effect...

Human capital production in the U.S. economy is no longer what it used to be. Graduation rates for high school and college have fallen (Card and Lemieux 2001; Heckman and Lafontaine 2007). As a result, the rate of growth of the stock of human capital has slowed considerably (Goldin and Katz 2008). At the same time, other countries are improving their educational attainment. Although the United ...

We use data with complete information on both rejected and accepted bank loan applicants to estimate the value of sample bias correction using Heckman’s two-stage model with partial observability. In the credit scoring domain such correction is called reject inference. We validate the model performances with and without the correction of sample bias by various measurements. Results show that it...

Yang (2020) recently argued for enhanced evidence–based decision making during sudden and widespread economic shocks such as the COVID-19 pandemic, but he lamented difficulty of acquiring data in a timely manner. One strategy is to implement an early warning survey system. This article describes Colorado’s experience with state administered local government officials shortly after governor’s st...