Re: T in $DES
Matts
I believe that the issue that you encountered is addressed in the NONMEM
output. Look for this text:
(WARNING 48) DES−DEFINED ITEMS ARE COMPUTED ONLY WHEN EVENT TIME
INCREASES. E.G., DISPLAYED VALUES ASSOCIATED WITH THE FIRST EVENT RECORD
OF AN INDIVIDUAL RECORD ARE COMPUTED WITH (THE LAST ADVANCE TO) AN EVENT
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
Quoted reply history
> On Jul 6, 2021, at 5:44 AM, Matts Kågedal <[email protected]> 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 further.
>
> I therefore derived T_DAY=T in $DES as below and output it in $TABLE.
> Why is T_DAY at TIME=0 equal to the time of the last observation for 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" variable T_DAY.
> Any advice would be appreciated.
> Matts Kågedal
>
> <image.png>
>
> <image.png>