Clarification on performance of mu referencing

Hi Training material distributed during an ICON training contains the following verbatim statements about mu referencing " Code already defined as Typical Value (TV), actual value (as recommended by Beal) are easy to convert: – TVCL = THETA(1)*AGE**THETA(2) – MU_5 = LOG(TVCL) – CL = EXP(MU_5+ETA(5)) Even better, linear relationship of all THETAS with MU’s: – LTVCL = THETA(1) + THETA(2)*LOG(AGE) – MU_5 = LTVCL – CL = EXP(MU_5+ETA(5)) " Can someone comment on why the second parameterization is "even better ? (besides the fact that estimates don't need to be bound) Thanks Sebastien Bihorel ******************************************************************** This e-mail and any attachment hereto, is intended only for use by the addressee(s) named above and may contain legally privileged and/or confidential information. If you are not the intended recipient of this e-mail, any dissemination, distribution or copying of this email, or any attachment hereto, is strictly prohibited. If you receive this email in error please immediately notify me by return electronic mail and permanently delete this email and any attachment hereto, any copy of this e-mail and of any such attachment, and any printout thereof. Finally, please note that only authorized representatives of Regeneron Pharmaceuticals, Inc. have the power and authority to enter into business dealings with any third party. ********************************************************************