st: Rescaling variables

[<suryadipta.roy@lawrence.edu>]

Hi,

I had another question on rescaling variables. At this 
point, I am trying to convert my some of my independent 
variables (running from 0 to 6) to standard normal 
variables. I have been able to do it by subtracting the 
numbers from the mean and dividing by the standard 
deviation for each group (I have an unbalanced panel of 
countries), but the problem comes for countries which had 
no within variation for that variable, since dividing by 
zero is giving missing observations in such cases. The 
following command does not work:

by code, sort: egen newvar=std(oldvar), since egen does 
not work with by.

Can anyone point me towards the correct command for direct 
conversion of numbers into their standard normals thereby 
circumventing the problem of dividing by zeros? Thanks as 
usual!

Suryadipta.


Suryadipta Roy, Ph.D.
Visiting Assistant Professor,
Department of Economics,
Lawrence University,
115 South Drew Street,
Appleton, WI-54911.
Phone: 920-832-7343.
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