RE: Describing variability

From: Leonid Gibiansky Subject:RE: [NMusers] Describing variability Date: Wed, 02 Apr 2003 11:54:16 -0500 Actually, this part >It looks like we agreed that >1. It is not good to use the model that did not converged. >2. It is not good to use the model that converged but does not provide >$COV >step. >3. Even if $COV step converged, this is not a guarantee that the >model is >correct, since it may be ill-conditioned any way. > was a joke (may be not too successful). I tried to show that taking the problem very rigorously would kill it (although each step will be perfectly logical): As to the 30-40%, this is a wish list, I do accept them up to about 100% if nothing, including FOCE, helps. However, there should be a limit here. It make no sense to use the parameter with 300% variability, this invalidate the entire model, you would get what you want on the fitting step, but get meaningless prediction on the simulation step. So, Bill, at least with you we are in full agreement !!! Sorry for confusion.... Leonid