[R] GLM: order of terms in model

[Christian Landry]

Dear R-helpers,

I have been analysing data using a GLM. My model is as follows:

mod <- glm (V ~ T + as.factor(A) + N, family="gaussian")

and using

anova(mod, test="F")

to get the analysis of deviance table and the fraction of deviance  
explained by each term.

T and A dominate with respect to their Deviance, with T having a  
larger effect than A (about twice)

However, if I reverse T and A in the model, I get that A now explains  
more deviance than T.

My questions are: 1) What is it due to?
				2) Is there any way around this? How do I find which model is  
best and/or can I use another method that won't be sensitive to the  
order of the terms.

Thanks,

Christian

Reply to: c.landry at umontreal.ca