Hello all,
I am working on a panel data of 200 firms from 1995-2019. Data is for a single industry. When I calculate the HHI from market shares, I get a time series of HHI for a 25 years and not for all firms to be used in panel. I tried to use the value of HHI for a particular year same for all firms. Is this the right approach? Is there any method by which I can get HHI for each firm so that I can run a meaningful analysis.
with regards