st: missing values included in conditions

["Zurab Sajaia" <zsajaia@hotmail.com>]

And another weird thing I just noticed and wanted to confirm that it's my 
mistake not Stata's :)


lets suppose we have a variable cond

   cond
      1
      1
      0
      0
      0
      .

if I write

.. count if cond==1

it will of course return 2. But using

..count if cond

gives result 3, as Stata includes missing in count as well. Somehow I was 
thinking that these two approaches were equivalent (and missings are always 
excluded) but was proven wrong.

So should missings be treated as "True" in this kind of conditions?

Thanks again,
Zurab


*
*   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/