Hello fellow Ecologers-
Yesterday I offered a response to the original posting on issues
surrounding use of AIC. Sadly, I failed to proof what I wrote and
thereby submitted some wrong stuff -- I wrote, "if 2 different measures
of fit (i.e., delta AIC value and r^2) support different
conclusions...." -- Of course, delta AIC is not a measure of goodness of
fit, it is a measure of the "quality" (i.e., information loss) of a
given model in comparison to other tested models. Hence, in my response
to point 3 of the original post, which read:
3. Use of other 'fit' statistics along with the model-selection
approach. I often see people reporting other statistics (e.g. p-vals,
r-squared) in combination with the AIC scores. My statistician friend
says that this is totally inappropriate, and uninformative.
My response should have been....since delta AIC and r2 measure different
things, I think it can be appropriate to report them together; not as
equal measures for model selection but as r2 informing on the relative
value of the AIC solution (i.e., if AIC indicates model X is the best,
but it has an exceptionally low r2 (assuming r2 is suitable to use as
the relationship is linear) then even the best model identified by AIC
is still pretty weak.
Sorry for any confusion.
Michael
