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From | Maarten Buis <maartenlbuis@gmail.com> |
To | statalist@hsphsun2.harvard.edu |
Subject | st: Re: Conditional Variable dropping in Stata |
Date | Fri, 2 Sep 2011 10:05:17 +0200 |
---Ana Gomez Lemmen Meyer wrote me privately: > I am an economics PhD student. I am trying to do a conditional drop > of variables in Stata, conditional on the mean of the variable being > smaller than a certain value. I saw your post about the program you > implemented for conditional dropping: > > http://www.stata.com/statalist/archive/2007-07/msg00224.html > > However, I do not know how to use the function you created. Do you > have a help menu for this function? I do not have a help file for that function and I do not intend to develop that program further. The reason is that I think such problems are easier solved from first principle. So in your case you would loop over a list of variables, compute the mean and drop that variable if that mean is less than some number: *-------------- begin example ---------------------- sysuse auto, clear // get a list of variables, // in this case all numeric variables // also see -help unab- // or just type them in a local macro ds, has(type numeric) local varl `"`r(varlist)'"' foreach var of local varl { sum `var', meanonly if r(mean) < 10 { drop `var' // just to keep a record of which // variable got dropped local dropped `"`dropped' `var'"' } } di as text "The following variables have been dropped:" di as result `"`dropped'"' *-------------------- end example ------------------------ (For more on examples I sent to the Statalist see: http://www.maartenbuis.nl/example_faq ) Hope this helps, Maarten -------------------------- Maarten L. Buis Institut fuer Soziologie Universitaet Tuebingen Wilhelmstrasse 36 72074 Tuebingen Germany http://www.maartenbuis.nl -------------------------- * * For searches and help try: * http://www.stata.com/help.cgi?search * http://www.stata.com/support/statalist/faq * http://www.ats.ucla.edu/stat/stata/