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st: RE: Using the -if- qualifier with a string variable
Yes, it can. The problem here lies in your use of
syntax indicating something different from what
you want. Or, you want Stata to guess what you
mean, but Stata can only go on what you actually say.
In your expression
you are expecting Stata to know somehow that you intend
be treated as the name of a variable but
to be treated as a literal string value.
However, as you are being told, it is interpreting
the latter as the name of a string variable,
with the problem in this case that no
such variable exists.
You need to use " " to signal a particular
.. if facility == "bir"
Note also that while most Stata users would
write something like that, there is
no reason why you should not write instead
... if "bir" == facility
Otherwise put, Stata attaches no
significance to the order of operands
in an assertion of equality -- just in
case you are thinking somehow that the
order of mention is important.
Similarly, we often say things like
... if x == 2
but that is just a carry-over from
mathematical convention leading
us to say something like
... if x = 2
... if 2 = x.
> Can the -if- qualifier be used with a string variable? If so,
> how is it
> done? I gave the following command, and had the shown result:
> . keep if facility==bir
> bir not found
> "facility" is a string variable and "bir" is one of the
> values "facility"
> takes. Thank you.
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