Dear Dr. Goslee:

I found some posts about potential interactions in MRM, and I wonder if it is acceptable to construct an interaction term as follows?
leaf1 = MRM(gendist ~ regiondist + envirdist +I(regiondist*envirdist) + moldist, mrank = TRUE, nperm=1000)

(I am using mrank = TRUE, incidentally, because our gendist matrix has a number of 0 values)

If this is not acceptable, what if I simply multiply the elements in the two matrices to generate a separate (interaction) matrix?  This is the usual way I have formed interactions in multiple regression models in SAS.

Which (if either) is preferable, and is there any problem with significance testing with an interaction term in the model?

Thanks much for your help.

Best,

Larry Leamy




Dr. Larry Leamy
Department of Biology
University of North Carolina at Charlotte
9201 University City Blvd.
Charlotte, NC  28223
Phone: (704) 687-8503
FAX: (704) 687-3128
Email: ljleamy@uncc.edu


	[[alternative HTML version deleted]]

