st: RE: observations differ with lrtest because of interaction terms

["Martin Weiss" <martin.weiss1@gmx.de>]

<>

http://www.stata.com/statalist/archive/2005-11/msg00718.html


HTH
Martin


-----Original Message-----
From: owner-statalist@hsphsun2.harvard.edu
[mailto:owner-statalist@hsphsun2.harvard.edu] On Behalf Of Meredith Carlson
Sent: Dienstag, 18. Mai 2010 23:13
To: statalist@hsphsun2.harvard.edu
Subject: st: observations differ with lrtest because of interaction terms

Hello Stata users,

I'm a Stata rookie, so please bear with me... I'm having problems when I run
lrtest with logistic regression to test for interaction between wealth index
and region variables.  The number of observations differ, not because of
missing values, but because of the interaction terms.  The model including
interaction has fewer observations because some have been dropped because of
this note...

note: _IsesXreg_3_9 != 0 predicts failure perfectly
      _IsesXreg_3_9 dropped and 4 obs not used


What exactly does this note mean?  What can I do to correct the number of
observations so lrtest will run?


Any advice would be greatly appreciated.  Thank you!


      

*
*   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/

*
*   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/