At 01:24 PM 8/9/2005, Suzy wrote:
Dear Statalistmembers,
I've appended 2 datasets with identical variables (columns). I'm
trying to drop certain variables, but notice that it duplicates my
observations/IDs. Although both datasets have identical variables,
the second dataset has only (.) missing values of the variable. I'm
not sure if that should affect my ability to drop variables. Is there
a quick fix with this? I'm using Stata 9.0.
The first question is, did you append correctly? Do the same
identical cases appear in both data sets, hence leading to your
duplicated observations? If so, it seems like you need to clean that
up. Does the 2nd data set really have all missing values on the
variable or variables, or did it just become that way when you did the
append? I'm wondering whether you actually appended or did some kind
of merge. Unless you expect things to be happening the way you are
describing, you may want to double-check what you did.
In any event, it is pretty easy to drop variables; just say -drop
varname-. The presence of missing data does not affect your ability
to do that. It sounds to me like the bigger issue is whether the
append was done right in the first place.
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