Log Normal data

From: Lewis Sheiner <76135.526@compuserve.com> Subject: Log Normal data Date: 29 Oct 1997 14:32:06 -0500 Dear Users, There may besome confusion on David's part or on mine. I am not sure what he means by "intersubject variability involving PK parameters." I would have thought this was variability modeled by eta. That is, for example, if $PK had CL = EXP(THETA(1)+ETA(1) then, under the FOCE mehtod and its variants, indeed, the actual model used by NONMEM would be that CL is distributed log-normally in the population. The strategy of modeling log(Y) does not automatically say anything about the distribution of the PK parameters; indeed if $PK had CL = THETA(1) + ETA(1), and the log(Y) vs log(F) model suggeested by David were used, the assumption would still be that CL is normally distributed, not log-normally! On the other hand, modeling log(Y) does accomplish a log-normal distribution for the intra-individual noise, and this is often a good idea.