[R-sig-eco] unplanned contrasts with categorical and continuous variables

[Rowan Brookes]

Hi,

I have conducted a general linear model with a mixture of continuous 
(POSITION; flower position on a raceme) and categorical (POLLEN and 
RESOURCE) variables.

The model looks like this: 
seedset.glm<-glm(MNSEED~POSITION*POLLEN*RESOURCE, family = gaussian, 
data = PR)

I have a significant interaction between position, pollen and resource 
but am unsure of how I should be doing an unplanned comparison when I 
have both categorical and continuous variables.  Can anybody direct me 
in the right direction?

I had initially turned flower position into a categorical variable, but 
had some opposition to this from reviewers.

Thanks very, very much,

Rowan