st: Confirming whether a variable is binary or continuous

[Bert Jung <bjung59@gmail.com>]

Dear Statalisters,

I am writing a short program to make a balance table that compares
covariates across a treatment and control group.  I am looking for a
way to confirm whether a variable is binary in order to use -prtest-
for proportions rather than -ttest- for continous variables.

One option is to check the actual data values and do -prtest- if there
are only 0's and 1's.  But a continuous but rare outcome could
accidentally also take these values, e.g. the number of
hospitalizations in the past 3 months.

Is there a safer way to confirm that a variable is binary?

Thanks for any pointers,
Bert
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