RE: Describing variability

From:"Hutmacher, Matthew [Non-Employee/1820]" Subject:RE: [NMusers] Describing variability Date:Wed, 2 Apr 2003 13:49:08 -0600 Hello everyone, An example of a model that may not give a COV step but is not necessarily ill-conditioned is a lag-time model or even a zero order infusion model. The reason is that the derivative does not exist at the change point, and if the point estimate is close to a data value, then the COV may not run. This is typically a problem with FOCE only. Matt