Does the internet increase competition? To address this question, I exploit two institutional details unique to Germany: (1) Some municipalities received glass fibre cables that cannot be upgraded to DSL; I use these municipalities as a treatment group with reduced online competition. (2) German...

This paper presents the first estimates of the causal effect of facilities for prenatal sex diagnosis on the sex ratio at birth in India. It conducts a triple difference analysis across cohort, birth order and sex of previous births. Treated births are those that occur after prenatal sex...

In this paper we survey methods to control for regression model error that is correlated within groups or clusters, but is uncorrelated across groups or clusters. Then failure to control for the clustering can lead to understatement of standard errors and overstatement of statistical...

In this paper we survey methods to control for regression model error that is correlated within groups or clusters, but is uncorrelated across groups or clusters. Then failure to control for the clustering can lead to understatement of standard errors and overstatement of statistical...

Does the internet increase competition? To address this question, I exploit two institutional details unique to Germany: (1) Some municipalities received glass fibre cables that cannot be upgraded to DSL; I use these municipalities as a treatment group with reduced online competition. (2) German...

This paper presents the first estimates of the causal effect of facilities for prenatal sex diagnosis on the sex ratio at birth in India. It conducts a triple difference analysis across cohort, birth order and sex of previous births. Treated births are those that occur after prenatal sex...