RE: Negative OFV number
For each observation (j)associated with an individual (i),you can
calculate the contribution to the overall - log-likelihood
(CLIKEIND(K,J))for any PK set of values (sampled from the current
population PK distribution if using MCPEM).
CONCNORM(K,J)=(DLOG(CONC(I,J))-DLOG(DABS(CPREDICTED(K,J))))/(SD)
CLIKEIND(K,J) =dLOG(SD)+CONCNORM(K,J)**2.0d0/2.0d0
SD is the standard deviation associated with your error variance model.
Dlog(SD) can be negative.
CONC(I,J) is the observed concentration for individual I at its jth
observation and Cpredicted(K,J) is the predicted concentration for that
individual (I has been omitted) for the kth simulated Pk vector (MCPEM
method).
OFV can be negative for both log or not log transformed data.
Serge Guzy
President, CEO; POP_PHARM;INC.
Quoted reply history
From: [email protected] [mailto:[email protected]]
On Behalf Of Yuhong Chen
Sent: Friday, December 17, 2010 1:19 PM
To: [email protected]
Subject: [NMusers] Negative OFV number
Dear All,
I am reviewing a PopPK report, and found the OFV is negative. The model
used the log transformed data. Is it can be the reason of negative OFV
number? Is the negative OFV number means the model may have problem? Any
suggestion will be greatly appreciated.
Warm regards,
Yuhong
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