Penny,
A simple solution using NONMEM is to put the different designs one after
the other and separate them with an EVID=4 data item on the first dosing
record for each design. You can a DESIGN data item value for each design
which then makes it simple to use the simulated data in a subsequent
NONMEM estimation run using ACCEPT or IGNORE on the $DATA record.
That way you can do the simulation just once and be sure to have all the
random effects (ETA) identical for each subject.
Best wishes,
Nick
On 10-Mar-17 12:11, Faelens, Ruben (Belgium) 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:*[email protected]
[mailto:[email protected]] *On Behalf Of *Zhu, Penny
*Sent:* donderdag 9 maart 2017 19:19
*To:* [email protected]
*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
PD Bio-Pharma CDMA
Sandoz
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Princeton, NJ 08540
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