st: to check if a variable already exists

[Jacob Wegelin <jwegelin@vcu.edu>]

Is there a way to check whether a variable is already defined, already exists? I'd like to write code of the following sort:


if (variable called performance is not yet defined) {
	gen performance=.
	}
replace performance=5 if name=George

Thanks for any ideas

Jake

Jacob A. Wegelin
jwegelin@vcu.edu 
Assistant Professor
Department of Biostatistics
Virginia Commonwealth University
730 East Broad Street Room 3006
P. O. Box 980032
Richmond VA 23298-0032
U.S.A. 
http://www.people.vcu.edu/~jwegelin
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