# Re: st: Simultaneous occurance

 From Kyle Hood To statalist@hsphsun2.harvard.edu Subject Re: st: Simultaneous occurance Date Tue, 18 Mar 2008 12:17:19 -0400 (EDT)

If the variables are named x1 and x2, could you not just sum them?

. gen x3 = x1 + x2

Then you get 0 when they are both zero, 1 when they differ, and 2 when they are both 1. If you want to return a 1 when x1 = x2, use

. gen x3 = ( x1 == x2 )

egen group will encode all four possible combinations

. egen x3 = group( x1 x2 )

Kyle

On Tue, 18 Mar 2008, Olga Lyashevskaya wrote:

```Dear all,

There are two binary variables in my sample, where 1
is presence and 0 is absence of the particular
characteristic. I want to identify those cases where I
get either both 0's or both 1's

Any suggestions?

Olga

____________________________________________________________________________________
Looking for last minute shopping deals?
Find them fast with Yahoo! Search.  http://tools.search.yahoo.com/newsearch/category.php?category=shopping
*
*   For searches and help try:
*   http://www.stata.com/support/faqs/res/findit.html
*   http://www.stata.com/support/statalist/faq
*   http://www.ats.ucla.edu/stat/stata/

```
```*
*   For searches and help try:
*   http://www.stata.com/support/faqs/res/findit.html
*   http://www.stata.com/support/statalist/faq
*   http://www.ats.ucla.edu/stat/stata/
```