From:"Rajanikanth Madabushi" 
Subject: [NMusers] Error model
Date:Mon, 21 Apr 2003 20:13:23 -0400

Dear NONMEM users
I have a query:
In NONMEM users guide VIII page no. 312 for the exogenous supplementation example, the
error model used has been mentioned as combined additive and ccv error model and is as follows:
$ERROR 
FP=THETA(7)+F ; adds endogenous component 
W=(1+THETA(8)*THETA(8)*FP*FP)**.5 
Y=F+W*ERR(1) 
My query to the group is:
1) Is this error model same as error model using two random variables like:

Y = F*(1+ERR(1)) + ERR(2) 

 2) What are the specific advantages and disadvantages of either of the error models?
 
Thanking in advance
Raj
 
Rajanikanth Madabushi
Post Doc Assoc
Dept. of Pharmaceutics
University of Florida
Gainesville
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