Re: [NMusers] RE: question about random seed for simulation

From: Kyle Baron <kyleb_at_metrumrg.com>
Date: Thu, 9 Mar 2017 17:56:37 -0600

To Ruben's question: mrgsolve simulates the subjects up front as well. The
subjects are identical across runs if the seed and number of subjects does
not change.

An illustration:
http://mrgsolve.github.io/2017/03/09/reproducible-results-with-set.seed/

Best regards,
Kyle


On Thu, Mar 9, 2017 at 5:11 PM, Faelens, Ruben (Belgium) <
Ruben.Faelens_at_sgs.com> wrote:

> Hi Penny,
>
>
>
> Nonmem indeed calculates each subject one after the other. The random
> values will therefore change. Maybe you can set the random seed every time
> you simulate 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,
> after which it runs the trial design; so the same subjects are sampled
> independent 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_at_globomaxnm.com [mailto:owner-nmusers_at_globomaxnm.com]
> *On Behalf Of *Zhu, Penny
> *Sent:* donderdag 9 maart 2017 19:19
> *To:* nmusers_at_globomaxnm.com
> *Subject:* [NMusers] question about random seed for simulation
>
>
>
> Dear All
>
> I have finished a multiple dose simulation for 600 subjects and want to
> perform a single dose simulation (different sampling time) on the same
> subjects (same ETA as the first simulation). I used the same seed for the
> simulation 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 the two simulation has different number TIME records. If so, I wonder
> what is 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 <(862)%20926-9079>
>
>
>
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>
> Sandoz
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>
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--
Kyle Baron, PharmD, PhD
Senior Scientist
Metrum Research Group

Received on Thu Mar 09 2017 - 18:56:37 EST

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