Bayesian fits
From: Paul Hutson <prhutson@pharmacy.wisc.edu>
Subject: [NMusers] Bayesian fits
Date: Thu, 01 Nov 2001 09:22:23 -0600
Hello, everyone.
Pardon what may be a trivial question from someone used to using ADAPT
for individual Bayesian fits. I have reviewed Part IV of the manual and
am uncertain about some items. In ADAPT, prior estimates and their variances
of the previously studied population are entered in the control stream,
while the estimates of the error model (usually linear or polynomial) is
entered elsewhere.
I think I understand that to use a group ("population") of subjects
with full or limited sampling to determine mean values of THETA and of
the individual ETAs, one would use the FOCE method: METHOD=CONDITIONAL
(or "1"), which would provide tempering of extreme estimates of individual
ETAs from the patient data in the input file. My understanding is that
the initial estimates of THETA and of ETA are indeed estimates, and that
they provide no understanding of the final estimates of THETAs and ETAs.
(Please correct me if I misunderstand this)
However, it is not clear to me how to code the control stream when previous
data regarding the estimates of THETA and ETA are known, so that the evaluation
of the local patient data includes for example the THETA and variance (ETA)
estimates of published PK parameters as well as including the new data
from the more recent data set being evaluated. Can someone shed light on
this?
Also, if it is possible to do so, is there strong feeling about isolating
or decreasing the weight of data obtained from parsimonious sampling when
the posthoc estimation of the individuals' ETAs are determined?
Thanks. As always, please excuse me if these are trivial questions.
There is always a feeling of discomfort when one transmits one's ignorance
around the world.
Paul
Paul Hutson, Pharm.D.
Associate Professor (CHS)
UW School of Pharmacy
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