Dear Nmusers,
We have a problem that is similar to that mentioned in "Modeling
concentration data with imprecise sampling time".
In a tumor model, we measure 3 concentrations simultaneously with resolution
in the seconds-range and high density. The dosing compartment 1 is measured
with a different and less accurate method. For technical reasons the start
of the time scale cannot accurately be adjusted, it has a nuisance jitter
which we must compensate for to avoid trouble with very steep initial
slopes.
I tried something like:
IF (CMT .NE.1) ALAG1 = EXP(MU_18+ETA(18))
IF (CMT .EQ.1) ALAG1 = EXP(MU_19+ETA(19))
but this does not work for MU/ETA 18 (it diverges), because dosing is in CMT
1.
Janet Wade recommended TSCALE, but if I understand the documentation, this
is a scaling (=multiplication of t), not a shift (=addition of t). Is there
something like TSHIFT?
Any ideas would be appreciated.
Dieter Menne
U Hospital of Zurich
Variant: Modeling concentration data with imprecise nuisance lag
Dear Dieter
The TSCALE is a factor that, obviously, scales. But, if you set the
boundaries appropriately it could only result in only higher or lower t
values.
Kind regards
Janet
Quoted reply history
-----Original Message-----
From: [email protected] [mailto:[email protected]] On
Behalf Of Dieter Menne
Sent: 03 June 2011 10:21
To: nmuser list
Subject: [NMusers] Variant: Modeling concentration data with imprecise
nuisance lag
Dear Nmusers,
We have a problem that is similar to that mentioned in "Modeling
concentration data with imprecise sampling time".
In a tumor model, we measure 3 concentrations simultaneously with resolution
in the seconds-range and high density. The dosing compartment 1 is measured
with a different and less accurate method. For technical reasons the start
of the time scale cannot accurately be adjusted, it has a nuisance jitter
which we must compensate for to avoid trouble with very steep initial
slopes.
I tried something like:
IF (CMT .NE.1) ALAG1 = EXP(MU_18+ETA(18))
IF (CMT .EQ.1) ALAG1 = EXP(MU_19+ETA(19))
but this does not work for MU/ETA 18 (it diverges), because dosing is in CMT
1.
Janet Wade recommended TSCALE, but if I understand the documentation, this
is a scaling (=multiplication of t), not a shift (=addition of t). Is there
something like TSHIFT?
Any ideas would be appreciated.
Dieter Menne
U Hospital of Zurich