RE: analysis of non-positive DV
Svetlana,
Can you clarify your model a bit more in terms of what is a parameter and
what is a covariate? You indicated that the DV is change from baseline. If
so, why do you have TBAS in the model? Is DV = TEFF - TBAS? If so,
it seems that your model should be written as:
DEFF = (TSLP*CP)**TALP (where DEFF = TEFF - TBAS).
Alternatively, you could define DV as the raw measurement following
treatment and create another column on your dataset for the observed
baseline response where TBAS is now a covariate rather than a parameter and
then your model could be as defined below:
TEFF = TBAS + (TSLP*CP)**TALP (where TSLP and TALP are parameters but TBAS
is a covariate).
Ken
Quoted reply history
-----Original Message-----
From: [email protected] [mailto:[email protected]] On
Behalf Of Vinogradova Svetlana
Sent: Wednesday, September 21, 2011 8:26 AM
To: [email protected]
Subject: [NMusers] analysis of non-positive DV
Dear NONMEM users,
I'm analyzing a dataset of 4 patients, there are 2 types of observations for
each patient - vehicle (say baseline) and dose (treatment). We want to
analyze our dataset in terms of (treatment-baseline). So I've modified my
dataset, and now I have only one "column" of observations for each patient:
DV= (treatment-baseline). But now I have some problems because I have some
negitive values in DV column. In case of some models it results in problems,
for example:
TEFF = TBAS + (TSLP*CP)**TALP
so TSLP should be positive but it's not that right...
Maybe there are some common methods to deal with this case?
Thanks a lot,
Svetlana