Re: [NMusers] BAYES method and initial estimate bounds

From: Bill Gillespie <bgillespiester_at_gmail.com>
Date: Tue, 22 Dec 2015 14:24:36 -0500

Hi Bob,

Thanks for the reply. On investigating further I see this happens when
NONMEM reports a THETA value of 1.34+154 in the PRDERR file. Would I be
correct in thinking that is the result of a floating point error somewhere
in the sampling process?

Thanks,
Bill

On Tue, Dec 22, 2015 at 12:40 PM, Bauer, Robert <Robert.Bauer_at_iconplc.com>
wrote:

> Bill:
>
> I just tested this on a simple script (see below), and the boundaries are
> imposed in BAYES analysis for me.
>
>
>
> $PROB RUN# Example 1 (from samp5l)
>
> $INPUT C SET ID JID TIME DV=CONC AMT=DOSE RATE EVID MDV CMT CLX V1X QX
> V2X SDIX SDSX
>
> $DATA example1.csv IGNORE=C
>
> $SUBROUTINES ADVAN3 TRANS4
>
> $PK
>
> MU_1=THETA(1)
>
> MU_2=THETA(2)
>
> MU_3=THETA(3)
>
> MU_4=THETA(4)
>
> IF (THETA(1)<1.63.OR.THETA(1)>1.8) WRITE(50,*) THETA(1)
>
> CL=DEXP(THETA(1)+ETA(1))
>
> V1=DEXP(THETA(2)+ETA(2))
>
> Q=DEXP(MU_3+ETA(3))
>
> V2=DEXP(MU_4+ETA(4))
>
> S1=V1
>
> $ERROR
>
> Y = F + F*EPS(1)
>
> $THETA (1.63, 1.67,1.8) 2.0 2.0 2.0
>
> $OMEGA BLOCK(4) VALUES(0.15,0.01)
>
> $SIGMA (0.6 )
>
> $PRIOR NWPRI
>
> $THETAP (2.0 FIX) (2.0 FIX) (2.0 FIX) (2.0 FIX)
>
> $THETAPV BLOCK(4) FIX VALUES(10000,0.0)
>
> $OMEGAP BLOCK(4) FIX VALUES(0.2,0.0)
>
> $OMEGAPD (4 FIX)
>
> $EST METHOD=BAYES INTERACTION NITER=1000 PRINT=100 CTYPE=3
>
> $COV MATRIX=R PRINT=E UNCONDITIONAL
>
>
>
> Robert J. Bauer, Ph.D.
>
> Vice President, Pharmacometrics R&D
>
> ICON Early Phase
>
> Office: (215) 616-6428
>
> Mobile: (925) 286-0769
>
> Robert.Bauer_at_iconplc.com
>
> www.iconplc.com
>
>
>
> *From:* owner-nmusers_at_globomaxnm.com [mailto:owner-nmusers_at_globomaxnm.com]
> *On Behalf Of *Bill Gillespie
> *Sent:* Tuesday, December 22, 2015 8:14 AM
> *To:* nmusers_at_globomaxnm.com
> *Subject:* [NMusers] BAYES method and initial estimate bounds
>
>
>
> Hi all,
>
>
>
> If bounds are specified in the $THETA statements for initial estimates,
> what, if any, effect do they have when the BAYES method is used?
>
>
>
> I initially thought they might work in conjunction with the prior
> specifications to implement truncated priors. However that does not seem to
> be true because statements like "IF(ABS(THETA(1)) > 10) EXIT 1 14"
> sometimes get tripped even when THETA(1) is bounded between -10 and 10 in
> the $THETA statement.
>
>
>
> Happy Holidays,
>
> Bill
>
>
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Received on Tue Dec 22 2015 - 14:24:36 EST

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