Dear Statalist,
I have information at cities and state level but want to aggregate it at the
state level using weighted averages (in a very manual way). For one of the
steps I am using the command �collapse (sum) variables, by (state year)� but
then I am getting zeroes where there were missing values because of the sum
function (it does not happen with the other collapse functions like sd,
mean, etc). I tried to use the option �cw� but since the missing values are
not for the same observation among the different variables I end up having
no observations at all.
So I would like to know if there is a way I could tell Stata not to collapse
missing values into zeroes when using (sum).
Thanks for any hint,
Best regards,
M�nica L.
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