Hello,

NONMEM has the following property related to intra-subject variability:

"During estimation by the first-order method, the exponential model and 
proportional models give identical results, i.e., NONMEM cannot distinguish 
between them."  So, NONMEM transforms F*DEXP(ERR(1)) into F + F*ERR(1).  
Is there an easy around it?  I try to code the logit transformation.  I cannot 
log-transform the original data as it is suggested in some publications 
including the presentation by Plan and Karlsson (Uppsala) because many values 
will be equal to plus or minus infinity.  Will NONMEM "linearize" the following 
code:
  Z = DLOG((F+THETA(10))/(1-F+THETA(10)))
  Y = DEXP(Z + ERR(1))/(1 + DEXP(Z + ERR(1)))

Thanks!
Pavel

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