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st: dot product across many variables


From   Paul Burkander <paul@burkander.com>
To   statalist@hsphsun2.harvard.edu
Subject   st: dot product across many variables
Date   Tue, 29 Nov 2011 12:11:41 -0500

Hi,

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?

Any thoughts?

Thanks,
Paul

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