Re: st: Different results from interaction term and Suest Command

[Maarten buis <maartenbuis@yahoo.co.uk>]

--- On Wed, 16/6/10, natasha agarwal wrote:
> First I introduce an interaction term of FDI*Development
> Level where Development Level=1 if higher developed and zero
> otherwise.
> 
> Second, I split the same and use the suest command and then
> test the difference in the slopes with the 'test' command.
> 
> However I get two different conflicting results. When I use
> the interaction term, I get that the two slopes are not
> significantly different from each other while when I use the suest
> command and then test for the slopes with the 'test' command I
> get that the slopes are significantly different from each other.

The two models are not the same if you have other variables in your
model: the second method implicitly adds interaction terms between 
development and all explanatory variables, while in your first
method there is only an interaction between development and FDI.

Hope this helps,
Maarten

--------------------------
Maarten L. Buis
Institut fuer Soziologie
Universitaet Tuebingen
Wilhelmstrasse 36
72074 Tuebingen
Germany

http://www.maartenbuis.nl
--------------------------


      

*
*   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/