Intercept changes when defining diff. reference categories
Posted: Tue Dec 08, 2009 8:40 am
Hallo
I have a problem concerning the reference category of categorical variables.
Normally I take a low reference category to fit the model. I observed that the intercept changes in function of the reference category I putted to the model. I also observed that if I take the lowest reference category, I get an error message that the matrix has gone negative. But if I take the middle category of the same variable, the model calculates without any problem.
Could anyone explain me why this happens?
Best regards, Jeannine
I have a problem concerning the reference category of categorical variables.
Normally I take a low reference category to fit the model. I observed that the intercept changes in function of the reference category I putted to the model. I also observed that if I take the lowest reference category, I get an error message that the matrix has gone negative. But if I take the middle category of the same variable, the model calculates without any problem.
Could anyone explain me why this happens?
Best regards, Jeannine