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

From: Ron Keizer <ron_at_pirana-software.com>
Date: Thu, 9 Mar 2017 16:17:50 -0800

Same for PKPDsim (when `seed` argument specified): all subjects sampled up
front, so inserting / removing observations has no effect on sampled
parameters.

Ron

On Thu, Mar 9, 2017 at 3:56 PM, Kyle Baron <kyleb_at_metrumrg.com> wrote:

>
> 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>
>>
>>
>>
>> PD Bio-Pharma CDMA
>>
>> Sandoz
>>
>> 1N025, 100 College Road West
>>
>> Princeton, NJ 08540
>>
>>
>>
>>
>>
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>
>
>
> --
> Kyle Baron, PharmD, PhD
> Senior Scientist
> Metrum Research Group
>
>

Received on Thu Mar 09 2017 - 19:17:50 EST

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