The correlation between wage premia and concentrations of firm activity may arise due to agglomeration economies or workers sorting by unobserved productivity. A worker's residential location is used as a proxy for their unobservable productivity attributes in order to test whether estimated...

Using data from the National Longitudinal Study of Adolescent Health, this study examines the impact of high school cohort composition on the educational and labor market outcomes of individuals during their early 20s and again during their late 20s and early 30s. We find that the positive...

This paper estimates the effects of friends' health behaviors, smoking and drinking, on own health behaviors for adolescents while controlling for the effects of correlated unobservables between those friends. Specifically, the effect of friends' health behaviors is identified by comparing...

We demonstrate a striking but previously unnoticed relationship between city size and the black-white wage gap, with the gap increasing by 2.5% for every million-person increase in urban population. We then look within cities and document that wages of blacks rise less with agglomeration in the...

We present evidence that benefits from agglomeration concentrate within race. Cross-sectionally, the black-white wage gap increases by 2.5% for every million-person increase in urban population. Within cities, controlling for unobservable productivity through residential-tract-by-demographic...

This paper examines the impact of youth friendship links on student's own academic performance (grade point average) using the Add Health. We estimate a reduced form, high dimensional fixed effects model of within cohort or grade friendship links, and use this model to predict each student's...