Hi Dongfen,
I agree with Leonid, and it is likely that $ABBREV PROTECT will do the
job. I however would encourage you to make an anonymous version of your
model so you can share it with the group if it does not solve the problem.
It might be informative to run the table step without estimation (i.e.
just with the initial values - only remove $EST and $COV) to see if PRED
is still zero. If not, there may be some numerical issue propagated from
EST/COV.
Anyhow, the problem is intriguing. Please let us know of your progress.
Hope it helps,
Jeroen
http://pd-value.com
jer...@pd-value.com
@PD_value
+31 6 23118438
-- More value out of your data!
On 23-02-2025 02:49, Leonid Gibiansky wrote:
Hi Dongfen,
Do you have IPRED computed correctly? Then there could be an error
during the PRED compute. Do you have NOABORT on EST step? You can try
to use NOHABORT and see what happen, or use $ABBREV PROTECT (in case
this would mask the error of PRED computations).
Another option is to get PRED from IPRED, see manual, like:
PREDU=1
If(COMACT==1) PREDU=IPRED
$TABLE ... PREDU ...
If PREDU=1 in the table, then there was an error on the step that
computes PRED values. If PREDU is reasonable but PRED is still 0, then
the problem is somewhere else.
You may also try FNLETA=0 (thus avoiding recompute of ETAs on the
table step): not sure whether it can help, but it is easy to try.
ADVAN13 is more stable than ADVAN6, so if you are using 6, you may try
13.
It looks like a numerical issue so anything that changes numerical
computations is worthwhile to try (NSIG, SIGL, TOL, etc.)
Also, check the .lst file and the dos windows in case of helpful error
messages.
Regards,
Leonid
On 2/22/2025 7:07 PM, Yuan, Dongfen [JRDUS] wrote:
Hello,
I am using an existing model to describe new study data. The
covariate model needs to be updated. The model is quite complicated:
time-varying PK and many IIVs. It takes a long time to converge. I
want to remove some of the IIVs to shorten the run time for covariate
search. Unexpectedly, after removing the IIV (one at a time), PRED=0
for all records. I got the same issue for multiple IIVs. It's a
proportional residual model on the original scale, IPRED was fine, so
dose was given. The model converged and parameter estimates were
close to values before removal, so it didn't seem like an estimation
issue. Before removal, PRED was fine and not a small number, so it
couldn't be a digit issue (I also tried to change format for $Table
but it did not work).
I am having a hard time understanding why. Apology that I cannot post
the full control stream here. It's NONMEM 7.5 and intel fortran. Hope
you can point me to the right direction. Really appreciate your
guidance!
Thank you,
Dongfen
