In statistical analysis using data such as accounting or household records, there is a common need to verify the effects of certain policies. A hurdle here is the problem of how to measure effects ...

subtitle: "Fixed Effects and Difference-in-differences" ...

TWFE is not just inefficient under staggered adoption; it is biased in a specific, diagnosable way. This chapter derives the exact bias, traces it to a geometric property of OLS, and shows where it ...

This estimator avoids the “forbidden comparisons” between early-treated and late-treated units that can bias TWFE estimates. The estimated average treatment effect on the treated (ATT) is 0.031 (p < 0 ...

The TWFE specification absorbs time-invariant city characteristics through city fixed effects and common temporal shocks through year fixed effects, isolating the differential change attributable to ...