Dear Researchers,

I have unbalance panel data set from 1990 to 2019, and after running the regression, the STATA showed me a message particularly after setting the data as a panel that (the years are from 1990 to 2019 but with a gap). So, do you think this will affect the analysis. I mean shall I treat it or I shall leave it? And, why this message appeared?

Secondly, since I have missing values in some of the variables, the STATA will drop these observations with missing values, so is there anyway to know the number of firms included in my analysis after running the regression?

Many thanks in advance.