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From | Nick Cox <njcoxstata@gmail.com> |
To | statalist@hsphsun2.harvard.edu |
Subject | Re: st: dot product across many variables |
Date | Tue, 29 Nov 2011 18:03:27 +0000 |
Consider a loop gen newdummy = 0 forval j = 2000/2010 { replace newdummy = newdummy + firstdummy`j' * seconddummy`j' } On Tue, Nov 29, 2011 at 5:11 PM, Paul Burkander <paul@burkander.com> wrote: > I have a data set that has two binary variables in each of several > years. I'd like to create a new variable that is the sum across all > years of the product of the two within year. > > For example, > firstdummy2000=1 > seconddummy2000=0 > firstdummy2001=1 > seconddummy2001=1 > > newdummy=(firstdummy2000*seconddummy2000+firstdummy2001*seconddummy2001)=1 > > There are so many years that it seems cumbersome to do it as above, > moreover the years might change over time and I'd like to be flexible. > > I thought perhaps a matrix command would work, doing a dot product? > * * 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/