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Re: [NMusers] Markov model dataset

From: Alison Boeckmann <alisonboeckmann_at_fastmail.fm>
Date: Fri, 12 Feb 2016 07:06:20 -0800

Here iis an explanation of why the error messages were being produced
by PREDPP.

At my request, Achim send me the $MODEL statement from the control
stream. $MODEL NCOMP = 4 COMP=(G0) COMP=(G1) COMP=(G2) COMP=(G3)

Compartment 1 is the default compartment for doses and observations,
because no compartment has the name CENTRAL or the attribute DEFOBS.

PREDPP always needs to compute a scaled compartment amount as the
argument F for the ERROR routine. When compartment 1 is off and PREDPP
needs to get the prediction from compartment 1 , the error messages
are produced.

0DATA REC    4: COMPARTMENT ASSOCIATED WITH THE PREDICTION IS OFF=
 0DATA
REC    5: COMPARTMENT ASSOCIATED WITH THE PREDICTION IS OFF 0DATA=
 REC
6: COMPARTMENT ASSOCIATED WITH THE PREDICTION IS OFF

Here's a work around, as Ahmed Suleiman suggested:

$MODEL NCOMP = 5 COMP=(G0) COMP=(G1) COMP=(G2) COMP=(G3)
COMP=(DUMMY,DEFOBS)

Also add to the end of the $DES block: DADT(5)=0

Now compartment 5 is default for observations and there are no
error messages.

Martin Bergstrand made a number of suggestions. The one that is directly
related to these error messages is to use "a  EVID = 4 dose to reset=
 all
compartments rather than resetting them 1 by 1."

EVID=4 is "reset and dose".  All compartments are set to 0, and then=
 the
dose is applied to compartment 1.

The data would look like this. No changes to $MODEL or $DES are needed,
because compartment 1 is never turned off.

C     ID    TIME  DOSE  DV     EVID=
  CMT    AMT   MDV     1     0 =
  0
0     1      1     1     1 =
    1     1     50     1   =
0      1     0
0     1     1     50     0   =
  4      1     1     1   =
1     1     50
0     2      2     0     1 =
    1     1     50     0   =
2      3     0
1     1     1     50     0   =
  2      4     0     1

Martin made other valuable suggestions but I am just trying to explain
the error messages.


Received on Fri Feb 12 2016 - 10:06:20 EST

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