Difference in difference with Unbalanced Panel

[Anuradha Saikia]

Dear Experts

I want to study the effect of regulatory intervention on a certain group of Companies. I have my treatment and control group as well as the post-treatment period. But my panel is unbalanced. Will it cause problems in the estimation?


Thanks and Regards
Anuradha

[Øyvind Snilsberg]

it may cause problems if selection is affecting the common-trend assumption

[Jared Greathouse]

How unbalanced is it

[Jeff Wooldridge]

Two-way fixed effects has some resiliency to unbalanced panels, but it should be applied to a flexible model. Is the intervention staggered or is it at the same time for all treated units?

[Anuradha Saikia]

Prof. Jeff Wooldridge my time period for the study is 2005-2020. For the treatment analysis , the period considered for all treated units is 2014 and beyond(till 2020).also the time periods are not uniform for each firm. in some periods from 2005-2009 are opted out or removed and for some 2005-2011.

[Anuradha Saikia]

Jared Greathouse the panel is unbalanced for 5 to 6 firms . and time periods which have been opted ou for these firms are both in categories 2005,2006,2007, 2008, 2009 and for some 2005-2011. so the time periods are not uniform for each firm per say, which might impact parallel trends assumption?