Only count certain rows

[carla Oth]

Hi all,

I have the following data structure:

DirectorID	Mgt_dummy	Year
1	1	2000
1	1	2001
1	0	100000
2	1	2003
2	1	2004
2	0	100000

Where Mgt_dummy is a dummy with a value of 0 if the Director was a manager in a certain year.

I want Stata to create a new variable counting the number of years a director has been manager. For instance, Director 1 is a manager for 2 years, and director 2 as well.


My current code is:

sort DirectorID year
by DirectorID: gen ManagerYears= _N
by DirectorID: keep if _n == 1


But with this code, my variable ManagerYears counts all rows, not just those where the Mgt_dummy variable has a value of 1.

How can I do this?


Thank you so much!

Best,

Carla

[Ali Atia]

If mgt_dummy can only be 1 or 0, and there is only one row per manager-year pair, you should be able to count the amount of years a director was manager by summing mgt_dummy:

bysort DirectorID: egen ManagerYears = total(mgt_dummy)

[carla Oth]

That's exactly it, thank you!