Dear group,
Recently I was running a sparse sampling animal data (one data per animal)
using NONMEM v6 & WFN and ran into this trouble:
"PARAMETER ESTIMATE IS NEAR ITS BOUNDARY
THIS MUST BE ADDRESSED BEFORE THE COVARIANCE STEP CAN BE IMPLEMENTED".
I searched the forum for any solution and found the message from Mark Sale
(Next Level Solutions).
My question: a) Is there any option to overcome this issue without suppressing
the message as suggested earlier?
b) What causes the above problem? Do I need to avoid specifying any boundary
for the thetas?
c) What does this message indicate? a poor selection of model? poor initial
estimates? narrow boundary? or any correlation issues with the estimates?
I highly appreciate your input. Thanks in advance
Regards,
Chandra Durairaj,
Post-doctoral Fellow,
Univ of Colorado Denver
