NBER Working Papers and Publications by Hannes Schwandt

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Working Papers and Chapters and Reporter Articles

March 2017Poorly Measured Confounders are More Useful on the Left Than on the Right
with Zhuan Pei, Jörn-Steffen Pischke: w23232
Researchers frequently test identifying assumptions in regression based research designs (which include instrumental variables or difference-in-differences models) by adding additional control variables on the right hand side of the regression. If such additions do not affect the coefficient of interest (much) a study is presumed to be reliable. We caution that such invariance may result from the fact that the observed variables used in such robustness checks are often poor measures of the potential underlying confounders. In this case, a more powerful test of the identifying assumption is to put the variable on the left hand side of the candidate regression. We provide derivations for the estimators and test statistics involved, as well as power calculations, which can help applied resear...
April 2016Mortality Inequality: The Good News from a County-Level Approach
with Janet Currie: w22199
Analysts who have concluded that inequality in life expectancy is increasing have generally focused on life expectancy at age 40 to 50. However, we show that among infants, children, and young adults, mortality has been falling more quickly in poorer areas with the result that inequality in mortality has fallen substantially over time. This is an important result given the growing literature showing that good health in childhood predicts better health in adulthood and suggests that today’s children are likely to face considerably less inequality in mortality as they age than current adults. We also show that there have been stunning declines in mortality rates for African-Americans between 1990 and 2010, especially for black men. The fact that inequality in mortality has been moving in...

Published: Janet Currie & Hannes Schwandt, 2016. "Mortality Inequality: The Good News from a County-Level Approach," Journal of Economic Perspectives, vol 30(2), pages 29-52. citation courtesy of

August 2014The 9/11 Dust Cloud and Pregnancy Outcomes: A Reconsideration
with Janet Currie: w20368
The events of 9/11 released a million tons of toxic dust into lower Manhattan, an unparalleled environmental disaster. It is puzzling then that the literature has shown little effect of fetal exposure to the dust. However, inference is complicated by pre-existing differences between the affected mothers and other NYC mothers as well as heterogeneity in effects on boys and girls. Using all births in utero on 9/11 in NYC and comparing them to their siblings, we show that residence in the affected area increased prematurity, low birth weight, and admission to the NICU after birth, especially for boys.
September 2012A Cautionary Note on Using Industry Affiliation to Predict Income
with Jörn-Steffen Pischke: w18384
Many literatures investigate the causal impact of income on economic outcomes, for example in the context of intergenerational transmission or well-being and health. Some studies have proposed to use employer wage differentials and in particular industry affiliation as an instrument for income. We demonstrate that industry affiliation is correlated with fixed individual characteristics, specifically parents' education and own height, conditional on the covariates typically controlled for in these studies. These results suggest that there is selection into industries based on unobservables. As a result the exclusion restriction in many IV studies of this type is likely violated.

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