首页|Royal Economic Society Annual Conference 2022 Special Issue on The New Difference-in-Differences
Royal Economic Society Annual Conference 2022 Special Issue on The New Difference-in-Differences
扫码查看
点击上方二维码区域，可以放大扫码查看
原文链接
NETL
NSTL
Oxford Univ Press
Each year, The Econometrics Journal organises a Special Session on a subject of current interest and importance at the Annual Conference of the Royal Economic Society. With these sessions, the journal intends to promote econometric theory and methods of substantive direct or potential value in applications and their actual empirical application. At the Society's online 2022 Conference, Xavier D'Haultfoeuille (CREST-ENSAE) and Jeffrey Wooldridge (Michigan State University) presented in a Special Session on The New Difference-in-Differences. Difference-in-differences (DiD) is a popular approach to estimating treatment effects from observational data. In its simplest form, it compares the change in outcomes over two periods between a treatment group that switches into treatment in the second period and a control group that remains untreated in both periods. Under the 'parallel-trends' assumption that the treatment group would have seen the same trend in outcomes as the control group if it would not have been treated, such a DiD estimates an average treatment effect on second-period outcomes in the treatment group. In empirical practice, this is often implemented by estimating a two-way fixed-effects (TWFE) model that specifies mean outcomes to be linear in group and time effects and the effect of treatment. Simply differencing outcomes over time kills the group effects, but leaves both the treatment effect (for the treatment group) and any time trend. A second difference, across groups, subsequently isolates the treatment effect. Indeed, the usual (least-squares) TWFE estimator of the slope parameter on the treatment indicator is the DiD estimator.
Jaap H. Abbring
展开 >
Tilburg University P.O. Box 90153 5000 LE Tilburg, The Netherlands
NETL
NSTL
Oxford Univ Press
