Statalist


[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

st: STATA drops squared terms from the model


From   [email protected]
To   [email protected]
Subject   st: STATA drops squared terms from the model
Date   Mon, 13 Jul 2009 18:17:44 +0200

Dear Statalist,

I estimate a log-log model with interaction term of the following form:

lnY = b0 + b1lnX + b2lnZ + b3lnX*lnZ + e

I want to test whether X and Z have a nonlinear effect on Y. Therefore, I add squared terms of X and Z to the model. When I estimate this model STATA drops X and Z from the model due to multicollinearity. The correlation coefficients between the unsquared and squared terms are very high (> 0,96). 

I have some problems interpreting this result. Does this mean that there is no non-linear effect?

Best regards

Phil

-- 
Neu: GMX Doppel-FLAT mit Internet-Flatrate + Telefon-Flatrate
für nur 19,99 Euro/mtl.!* http://portal.gmx.net/de/go/dsl02
*
*   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/



© Copyright 1996–2024 StataCorp LLC   |   Terms of use   |   Privacy   |   Contact us   |   What's new   |   Site index