RE: DV simulation problem

From: VPIOTROV@PRDBE.jnj.com Subject: RE: [NMusers] DV simulation problem Date:Sun, 8 Jun 2003 19:46:00 +0200 Toufigh, As Sriram pointed out, if your goal is a predictive check, or if you are interested in concentration prediction intervals (PI), you have to focus on simulated DV, however, IPRE is also of interest as you may want to know which part or PI comes from (estimated) interindividual variability, and which is explained by residual variability. The latter may be surprisingly high, as Sriram mentioned. It seems NONMEM tends to overestimate residual variability, that becomes especially obvious in case of dense data. I am not sure playing with the residual variance is a correct way to solve the problem. I would try to use a sample variance that one can easily obtain from (weighted) individual residuals. It is quite robust since is based on a lot of observations (again if you have dense data). Best regards, Vladimir