Output EPS(1) after an $EST step?

All, Is there a way to recover epsilons after an $EST step? The difference between DV and IPRED is epsilon for a simple additive error model. However, with a mixed proportional and additive error model, I can't see a way to separate the two epsilon contributions to DV-IPRED. $TABLE EPS(1) after an $EST step provides a column of zeros, and the NONMEM manual indicates this is the expected behavior. Warm Regards, Mike Dodds

The only way that I know is to use SD=SQRT(IPRED**2*THETA(10)**2+THETA(11)**2) Y=IPRED+SD*EPS(1) RES=DV-IPRED IWRES = RES/SD ; same as EPS(1) $SIGMA 1 FIX Leonid -------------------------------------- Leonid Gibiansky, Ph.D. President, QuantPharm LLC web: www.quantpharm.com e-mail: LGibiansky at quantpharm.com tel: (301) 767 5566

Dear Mike, Even with a simple additive error model the IRES (=DV-IPRED) is not going to be epsilon, unless the number of observations per subject goes towards infinity (and the model is correct in all its parts). For an additive + proportional the corresponding residual (IWRES) is Y=IPRED+EPS(1)*IPRED+EPS(2) IRES = IPRED-DV SIG11=SIGMA(1,1) SIG12=SIGMA(1,2) SIG22=SIGMA(2,2) IWRES = IRES/SQRT(SIG11*IPRED**2+SIG22+SIG12*IPRED) If SD(IWRES) is approximately 1, the IWRES probably agrees reasonably with epsilon. If it is lower, there is epsilon shrinkage (also output by NONMEM) and the agreement between epsilon and the residual is lost. Best regards, Mats Mats Karlsson, PhD Professor of Pharmacometrics Dept of Pharmaceutical Biosciences Faculty of Pharmacy Uppsala University Box 591 75124 Uppsala Phone: +46 18 4714105 Fax + 46 18 4714003