Re: Mixed Models
Hi,
I don't really understand the post from Indrajeet (what is a 'true' value?).
The following code is legal in NM7:
IF (WT<=350) THEN
CL=THETA(1) + ETA(1)
ELSE
CL=THETA(1) + ETA(2)
ENDIF
but won't work in NMVI where you have to use f77 syntax for logical expressions:
IF (WT.LE.350) THEN
CL=THETA(1) + ETA(1)
ELSE
CL=THETA(1) + ETA(2)
ENDIF
Perhaps Shankar is using NMVI?
Quoted reply history
On a more practical note, the apparent WT dependence of the disposition model might disappear if you use normal fat mass instead of total body WT to scale the PK parameters (see Anderson & Holford 2009)
Nick
Anderson BJ, Holford NHG. Mechanistic basis of using body size and maturation to predict clearance in humans. Drug Metab Pharmacokinet 2009; 24: 25-36.
On 21/03/2012 5:22 p.m., indrajeet singh wrote:
> Shankar:
>
> I hope you are not, but you can not change true value variables in conditional statements
>
> eg.
> IF (...) THEN
> CL= TVCL+eta(1)
> ELSE
> CL=TVCL+eta(2)
> ENDIF
>
> There are alternate ways of doing that by creating new identifier for your WT ranges.
>
> I hope this helps.
>
> On Wed, Mar 21, 2012 at 10:39 AM, Shankar Lanke < [email protected] < mailto: [email protected] >> wrote:
>
> Dear All,
>
> I am running a pop pk IV infusion data, the observed values are
> collected form obese patients and normal patients.
> I used WINONLIN to estimate the initial parameters. Patients who
> weigh more than 350 lbs are following 2CM and less than 350 are
> following 1CM. I confirmed the models based on AIC, CV% (of
> parameters), graphical representation. Vd increases with weight (1CM).
>
> So I used IF(WT<=350)THEN statements from the beginning ($MODEL, $
> PK, $ DES, $THETA). I have the following error.
> AN ERROR WAS FOUND IN THE CONTROL STATEMENTS.
> AN ERROR WAS FOUND ON LINE 10 AT THE APPROXIMATE POSITION NOTED:
> IF(WT<=350)THEN
> X
> THE CHARACTERS IN ERROR ARE: IF
>
> Thank you very much in advance for your suggestions.
>
> Regards,
> Shankar Lanke Ph.D.
>
> --
> Indrajeet Singh,PhD
> Sr. Clinical Pharmacokineticist
> Abbott Labs, North Chicago, IL
--
Nick Holford, Professor Clinical Pharmacology
Dept Pharmacology& Clinical Pharmacology, Bldg 505 Room 202D
University of Auckland,85 Park Rd,Private Bag 92019,Auckland,New Zealand
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