I have GLS regression coefficients of the 'best' model from four different islands in my study system. I would like to compare how the 'best' model from island 1 predicts the response variable on island 2, 3 and 4. What would be a suitable method to do this?
I'm unsure as to whether I should compare the slopes of each island to see whether they differ significantly from each other (and if so, how I would even go about doing this) or whether the best approach would be to use predict() and proceed via this route (assuming I can use predict() when using ML GLS).
EDIT - I'm unable to reply to Silverfish's comment (below) as my reputation is too low. I have instead updated my question here to address his response.
In short, I would like to see how well/poorly the island 1 model applies to island 2/3/4. In theory, I expect the 'best' models for each island to transfer well to every other island but I would like to formally test this.