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 -----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
