st: simple method to identify string variables?

[David Radwin <radwin@berkeley.edu>]

Dear Statalisters,

Is there a simple way to identify string variables using an if 
statement? As an obviously contrived example, suppose I wanted to use 
the -mean- command for all numeric variables. I would get this error 
message:

. sysuse auto,clear
. mean _all
varlist:  make:  string variable not allowed
r(109);

Can I limit the command to numeric variables only? I suspect there is 
an easy, even obvious solution, but I can't find it anywhere.

Thanks,

David
--
David Radwin, Principal Analyst // radwin@berkeley.edu
Office of Student Research, University of California, Berkeley
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