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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?
>
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