Barbara Engels <engels.ba@gmail.com> :
You should certainly use cluster-robust SE to account for repeated
observations, but how could you include FE and a dummy for treatment
group? With a post dummy, and a treatment dummy, and the interaction,
there would be a severe perfect collinearity problem.
On Wed, Jan 2, 2013 at 3:49 PM, Barbara Engels <engels.ba@gmail.com> wrote:
> Dear Stata people,
>
> I am currently working on a difference-in-differences model in its simplest form - treatment and control group, pre- and post-intervention period.
> However, I got a large panel data set and I wonder what is the best way to estimate the DID in Stata to account for flaws like serial correlation.
> Should I go for a simple
>
> reg y x incl. interaction term, ROBUST
>
> Or should I apply clustering?
> Or even xtreg with fe?
>
> Any help is greatly appreciated.
>
> Thanks a lot, happy 2013!
>
> Barbara
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