Before revision:  We then propose another estimator that does not rely on any treatment effect homogeneity assumption. We revisit two empirical articles that have estimated two-way fixed effectsregressions. In both cases, around half of the weights attached to those regressions are negative. In one application, our new estimator is of a different sign than the first two-way fixed effects estimatorwe study, and significantly different from the second one .
After revision:  We then propose another estimator that is robust to heterogeneous treatment effects. In an application, it is of a different sign than the first two-way fixed effects estimatorwe study, and significantly different from the second one .