NONMEM Users Network Archive

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RE: question about random seed for simulation

From: Faelens, Ruben <Ruben.Faelens>
Date: Thu, 9 Mar 2017 23:11:34 +0000

Hi Penny,

Nonmem indeed calculates each subject one after the other. The random value=
s will therefore change. Maybe you can set the random seed every time you s=
imulate t=0, based on the subject ID?
This may also depend on your data file; have you tried ordering on time (so=
 the first 50 rows are all t=0 for subject 1 to 50) ?

This largely depends on the simulation software and its design:
As an example: Simulo samples all subjects together at simulation start, af=
ter which it runs the trial design; so the same subjects are sampled indepe=
ndent of subsequent trial design.

I do not know about other tools (TS.2, simulx, mrgsolve), maybe the authors=
 of these tools can specify?

Kind regards,
Ruben Faelens

From: owner-nmusers
 Behalf Of Zhu, Penny
Sent: donderdag 9 maart 2017 19:19
To: nmusers
Subject: [NMusers] question about random seed for simulation

Dear All
I have finished a multiple dose simulation for 600 subjects and want to per=
form a single dose simulation (different sampling time) on the same subject=
s (same ETA as the first simulation). I used the same seed for the simulat=
ion step, it turned out the first subject was the same and the rest of the =
subjects are not and I am not sure whether this was due to the fact that th=
e two simulation has different number TIME records. If so, I wonder what i=
s the proper way to set the simulation seed so that the ETAs for the second=
 simulation will be identical to the first one.

I know that I could output the individual parameter estimate from the first=
 simulation and import them into the second one. But I was thinking if the=
 random seed can be synchronized between the two simulation, it could be an=
 easier solution.

Your help is very much appreciated!

Thank you very much and best regards!

Penny (Peijuan) Zhu, Ph.D.
Associate Director Clinical Pharmacology

Cell: 862-926-9079

PD Bio-Pharma CDMA
1N025, 100 College Road West
Princeton, NJ 08540

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Received on Thu Mar 09 2017 - 18:11:34 EST

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