RE: [NMusers] ISAMPLE under SAEM and IMP

From: Bauer, Robert <Robert.Bauer_at_iconplc.com>
Date: Wed, 8 Apr 2015 17:02:33 +0000

Xinting Wang:
Generating each sample in SAEM is computationally more expensive in SAEM, and so ISAMPLE of 2-10 is generally done. You may try increasing ISAMPLE=3 or 5 in SAEM. Furthermore, convergence testing is only a guide, Review the .ext file and be satisfied by visual inspection that the parameters are not directionally changing, and are just randomly fluctuating.

Robert J. Bauer, Ph.D.
Vice President, Pharmacometrics R&D
ICON Early Phase
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From: owner-nmusers_at_globomaxnm.com [mailto:owner-nmusers_at_globomaxnm.com] On Behalf Of Xinting Wang
Sent: Tuesday, April 07, 2015 7:42 PM
To: nmusers_at_globomaxnm.com
Subject: [NMusers] ISAMPLE under SAEM and IMP

Dear all,
I have a question regarding the setting of ISAMPLE under SAEM and IMP method in Nonmem 7.2.
I have noticed that in the NONMEM manual, the default setting of ISAMPLE for IMP is 300, and 2 for SAEM. Well it was well explained about the general guidance of ISAMPLE for IMP, i.e. might need to float to 1000-3000 in case of sparse samples. However, the setting for ISAMPLE under SAEM is not explained that much.
Additionally, in the examples provided in the manual most of ISAMPLE setting is in its hundreds or more for IMP, this option under SAEM is mostly 2. I understand that with a lower value the computation is fast, but why is there's such a big difference in terms of setting sample number per subject?
The reason I am asking this is because of a diffitulty to achieve convergence in the burn-in step using below estimation method:

$EST MET=SAEM INTER NBURN=2000 NITER=1000 PRINT=10 NOABORT NOPRIOR=0 ISAMPLE=2 SIGL=6 CTYPE=0
SEED=150159 FILE=Saem.ext

$EST MET=IMP INTER NITER=2000 ISAMPLE=1000 PRINT=10 SEED=150987 SIGL=6, CTYPE=3 FILE=Imp.ext
Thanks very much for your explanation.
Best Regards

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Xinting
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Received on Wed Apr 08 2015 - 13:02:33 EDT

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