Re: st: appended datasets and trying to drop variables

["Richard. Williams" <Richard.A.Williams.5@nd.edu>]

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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