age of the firm

[max tailler]

Dear Statalisters,

i sort firms by their age. i define the firm age as the difference between the current year and the first year that a firm enters the Compustat database .


Which variable ( the entry of firm in compustat database) will classify the age of firm?
not sure if I should just use : firm id , datadate, or ipodate

[Carlo Lazzaro]

Max:
as we do not know how you named the variable resulting from the subtraction that you mention in the first line of your post, I find impossible to reply positively.
That said, please note that while Stata will accept -firm_age-, reject -firm age- as it reads it as two different variables.