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Re: T in $DES

From: Alison Boeckmann <alisonboeckmann>
Date: Sun, 11 Jul 2021 12:16:58 -0700

The question has been answered correctly by the various people who comme=
nted recently.
Dennis asked me to "explain the inner workings."
This topic has been discussed in the past. See the mail archive web site=

https://www.mail-archive.com/nmusers

A good search is for "Warning 48". This will bring up a number of emai=
ls re:
"Question regarding Calculation Process in $DES BLOCK"
You will find a discussion of the issue in these emails, from June 2011=
.

On Tue, Jul 6, 2021, at 7:28 AM, Dennis Fisher wrote:
> Matts
>
> I believe that the issue that you encountered is addressed in the NONM=
EM output. Look for this text:
>
> (WARNING 48) DES−DEFINED ITEMS ARE COMPUTED ONLY WHEN EVENT T=
IME
> INCREASES. E.G., DISPLAYED VALUES ASSOCIATED WITH THE FIRST EVENT REC=
ORD
> OF AN INDIVIDUAL RECORD ARE COMPUTED WITH (THE LAST ADVANCE TO) AN EV=
ENT
> TIME OF THE PRIOR INDIVIDUAL RECORD.
>
> The wording is arcane but the basic message is that, for each subject,=
 the first values for DES computed entries are not what you expect.
> Despite this, NONMEM is "doing the right thing".
> I defer to Alison Boeckmann to explain the inner workings.
>
> Dennis
>
> Dennis Fisher MD
> P < (The "P Less Than" Company)
> Phone / Fax: 1-866-PLessThan (1-866-753-7784)
> www.PLessThan.com <http://www.plessthan.com/>
>
>
>
>> On Jul 6, 2021, at 5:44 AM, Matts Kågedal <mattskagedal
m> wrote:
>>
>> Hi all,
>> I have a question regaring T in $DES.
>> I have a time-varying covariate that is derived based on an explicit =
equation and then use in a differential equation.
>> I got some funny results in the output table and investigated a bit f=
urther.
>>
>> I therefore derived T_DAY=T in $DES as below and output it in $TABL=
E.
>> Why is T_DAY at TIME=0 equal to the time of the last observation fo=
r the patient? I was expecting it to be Zero (same as Time). Seems to be=
 the same for all IDs in the dataset.
>> Below is the output created in $TABLE including the "derived" variabl=
e T_DAY.
>> Any advice would be appreciated.
>> Matts Kågedal
>>
>> <image.png>
>>
>> <image.png>

--
  Alison Boeckmann
  alisonboeckmann


Received on Sun Jul 11 2021 - 15:16:58 EDT

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