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Irae119
Posted: Thu Apr 17, 2008 1:14 pm
Guest
Hi,

I have a polytomous logistic regression with a dependant variable with three outcomes: success, negative failure, positive failure. It was a continuous variable put in three categories because below 87% or over 113% the operation is considered a failure. The problematic independent variable is continuous, mean temperature. In the univariate analysis, the OR is near 1 but in the multivariate analysis, the OR jumps to 159.9. What could explain this ?

Thanks in advance !
Richard Ulrich
Posted: Fri Apr 18, 2008 1:08 am
Guest
On Thu, 17 Apr 2008 19:14:52 EDT, Irae119
<sophie_r_l_dubuc@hotmail.com> wrote:

Quote:
Hi,

I have a polytomous logistic regression with a dependant variable with three outcomes: success, negative failure, positive failure. It was a continuous variable put in three categories because below 87% or over 113% the operation is considered a failure. The problematic independent variable is continuous, mean temperature. In the univariate analysis, the OR is near 1 but in the multivariate analysis, the OR jumps to 159.9. What could explain this ?

Thanks in advance !


Are you saying that the linear trend is not-significant,
whereas the quadratic possibility (3 groups) has a
high OR? That should not be hard to demonstrate
from a graph.

--
Rich Ulrich
http://www.pitt.edu/~wpilib/index.html
 
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