RE: [NMusers] hardware question

Hi Tom

Thanks for chiming in! I agree with regard to testing to ensure that the
model hasn't hit a local minimum and can see that this would potentially
result in compiler and platform related differences, but as far as I can
tell thus far, Nonmem VI seems to be somewhat less likely to hit local
minima then Nonmem V. Is that consistent with your experience?

There is one other point that users might consider. Owing to the length of
time that Nonmem V was the standard, there were rather a lot of recommended
changes to the software and my understanding is that not all users had all
changes implemented. Therefore the differences that came up in Nonmem V
between different sites could be at least partly attributable to differences
in source code as well hardware and compiler differences.

Diane

> -----Original Message-----
> From: Ludden, Thomas (MYD) [mailto:luddent_at_iconus.com]
> Sent: Monday, January 08, 2007 12:28 PM
> To: drmould_at_attglobal.net; Mark Sale - Next Level Solutions
> Cc: nmusers_at_globomaxnm.com
> Subject: RE: [NMusers] hardware question
>
> Dear all,
>
> As Diane Mould states, NONMEM VI is generally more stable than NONMEM V.
> However, it has been our experience that, when using a conditional
> estimation method, stopping at a local minimum and compiler- and
> platform-related differences in termination may occur with NONMEM VI.
>
> Whenever conditional estimation is used, it is prudent to employ
> multiple runs with different initial estimates and to repeat runs with
> final estimates used as initial estimates in an attempt to detect local
> minimums or overall instability.
>
> Tom
>
> -----Original Message-----
> From: owner-nmusers_at_globomaxnm.com [mailto:owner-nmusers_at_globomaxnm.com]
> On Behalf Of Diane R Mould
> Sent: Monday, January 08, 2007 10:43 AM
> To: 'Mark Sale - Next Level Solutions'
> Cc: nmusers_at_globomaxnm.com
> Subject: RE: [NMusers] hardware question
>
> Hi Mark
>
> Yes, clients often want to be able to reproduce a contractor's results
> by
> re-running the final model on their own system and I would also say that
> the
> regulators do as well. For Nonmem V, therefore, having different
> compilers
> and processors is a valid concern. I think Peter Bonate had a poster at
> AAPS some years ago investigating differences in hardware and compilers.
>
> However for Nonmem VI, our experience thus far has been that it is not
> as
> sensitive to compilers and hardware. In fact it also appears to be less
> sensitive than Nonmem V was to the run termination status as well (so
> even
> if the runs terminate, parameter estimates are generally pretty good, as
> is
> the OBJ), which I think is consistent with what Tom Ludden presented
> when he
> gave a preview of Nonmem VI. So for your hardware, I would guess if
> Nonmem
> VI is the system you will be using for future consulting jobs, you
> should
> not have problems duplicating your results on other hardware.
>
> Good luck finding a buyer :-)
>
> Diane
>
> > -----Original Message-----
> > From: owner-nmusers_at_globomaxnm.com
> [mailto:owner-nmusers_at_globomaxnm.com]
> > On Behalf Of Mark Sale - Next Level Solutions
> > Sent: Monday, January 08, 2007 10:18 AM
> > Cc: nmusers_at_globomaxnm.com
> > Subject: [NMusers] hardware question
> >
> > For those of you who don't keep track of such things, Intel is, today,
> > releasing the desktop (non-gaming) quad core CPU. I'm thinking of
> > redoing my entire network, buying maybe 8 quad core machines for the
> GA
> > application, as well as parallel NONMEM. My question is, as a
> > consultant, my clients frequently want to re-run final models on their
> > hardware - and I assume that the regulators do as well. How much of a
> > problem will it be if I set up my system as 64 bit Vista (or XP) with
> > the Intel 64 bit compiler? There will be times when the 64 bit result
> > will be different than the 32 bit (as there are times when different
> > compiler setting, different compiler etc give different results). Is
> > anyone out there planning to move to 64 bit Intel? Will anyone be able
> > to rerun my results? It seems, as far as I can tell, the 64 bit system
> > is maybe 20-40% faster than a comparable 32 bit system. So, quad
> core,
> > 64 bit and NONMEM VI (which is faster than NONMEM V), should make a
> > noticable difference.
> >
> >
> > Thanks
> > (anyone out there want to buy 12 slightly used dual core computers?)
> >
> > Mark Sale MD
> > Next Level Solutions, LLC
> > www.NextLevelSolns.com
> >
> >
>
>
>
>
>
>
>
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Received on Mon Jan 08 2007 - 12:47:16 EST