RE: covariates

From: Renee Ying Hong [mailto:yinghong@pharm.usyd.edu.au] Subject: RE: [NMusers] covariates Sent: Monday, September 20, 2004 2:31 AM Hello, Nick and Leonid, I ran NONMEM following your instructions. It is the other way around this time Firstly, I ran the power model by adding WT to all the parameters simultaneously, which was suggested by Leonid. OFV increased double compared to the basic model. Therefore, I didn't keep on going. Then I ran the allometric model at the same time as suggested by Nick. OFV decreased 20.4. The THETA and relative standard error is OK, However, ETA of CL decreased dramatically, from 0.0612 (CV%24.7%) to 0.000291(1.7%). The standard error of ETA (CL) is 0.0626, which suggested the estimate of ETA(CL) is not correct. I attached the diagnostic plots. In addition, I have a few questions: 1. can I report the CV% of CL is 1.7%? 2. Covariance is aborted sometimes when I ran NONMEM even the minimization is successful. How can it be avoided? 3. Leonid suggested me to plot ETAs vs WT. Is ETA calculated from EXP (CLi / TVCL)? Please comment! Screening covariates is a painstaking process. And I found myself very lucky having your two NONMEM artists to help me do it properly. I benefit a lot from your friendly arguments! Kind Regards, Renee