Re: st: Taking averages, etc.

[David Kantor <dkantor@jhu.edu>]

For averages (-summarize-) and just about any similar measure or analytical 
procedure, Stata ignores the missing values -- as if the observations in 
question were not present.  This happens automatically.

(This is different from an expression such as (a + b + c) / 3 , where a 
single missing value spoils the result.)

Note that for commands that take several variables together, they generally 
work on the set of observations having no missing values on all the 
variables under consideration.  So, as you adjust the set of variables, the 
set of observations may shift -- depending on which variables have missing 
values on what observations.

I hope this helps.

At 05:25 PM 12/16/2003 -0500, Adrian de la Garza wrote:

> Hello, everyone!
>
> Can anyone tell me if it's possible to tell Stata to ignore missing
> observations when computing averages, etc.? I think that if there is a
> missing value in the observations considered, the average computed would
> be then missing too... and I need it to intelligently choose how many
> observations to use depending on whether observations are available,
> etc.
>
> Thanks!
> Adrian
David Kantor
Institute for Policy Studies
Johns Hopkins University
dkantor@jhu.edu
410-516-5404

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