r Squared from NONMEM

Can anyone tell me how to compute an r-squared (or equivalent) from NONMEM output. I have a covariate that markedly diminishes the objective function value (decrease by 11.5 with an associated chi-square p-value of 0.001); however, I don't know how to determine how much of the overall variability inclusion of this covariate accounts for. In a simple linear regression we get r-squared. What parameter should I look at in a NONMEM output? Any assistency you could provide would be very much appreciated.

1) I would not call a OF drop of 11 points a large change; in fact, I'm betting that you can not even see a difference in your goodness-of-fit plots. What effect did the inclusion of this covariate have on your eta - estimate for CL? If it decreased (e.g., before you added the covariate you CV% was 27%, and after you added the covariate it was 18%) that's what you want - your covariate is explaining some part of the residual error for this parameter. If not, I'm not sure I'd keep the covariate in the model even with an 11 point drop. 2) R2 is a terrible goodness-of-fit metric and should not be used. See Sheiner LB and Beal SL. Journal of Pharmacokinetics and Biopharmaceutics (1981) 9:503-512. for the reasons why. [EMAIL PROTECTED] Sent by: [EMAIL PROTECTED] 15-May-2008 10:23 To [email protected] cc Subject [NMusers] r Squared from NONMEM Can anyone tell me how to compute an r-squared (or equivalent) from NONMEM output. I have a covariate that markedly diminishes the objective function value (decrease by 11.5 with an associated chi-square p-value of 0.001); however, I don't know how to determine how much of the overall variability inclusion of this covariate accounts for. In a simple linear regression we get r-squared. What parameter should I look at in a NONMEM output? Any assistency you could provide would be very much appreciated. Plan your next roadtrip with MapQuest.com: America's #1 Mapping Site. <<image/jpeg>>