I am working with pediatric data on a popPK model. If I want to include weight in my base model, in the Parameter/Structural tab can I simply include it from the covariate list using the Backward direction, not center it around the median, and on the fixed effects tab, freeze the initial estimate at 1 to set it to the power of 1? I want to end up with this: CL (L/kg/h) = THETA(1)WTEXP(ETA(1)) V (L/kg) = THETA(2)WTEXP(ETA(2)) Thanks for any help, Kevin