Hello! I have hunted far and wide on the net in an attempt to answer this. Essentially, I'm trying to combine two AIC scores from different parts of a single data set. I have two models (of the same type: nonlinear least squares fitting a growth curve to population data) that each predict about half of the data (imagine two logistic growth curves attached end to end), each half with a different AIC. For reasons inherent in the study, the fitting process is split at a particular time point. I am interested in finding the combined AIC of both curves to represent the single, total AIC of the combined models. I have been told that this is possible, but I don't know how. Any suggestions are much appreciated!