yway. Good luck with your
project!
Please excuse my brevity, this was sent from a mobile device
From: Tingjie Guo
Sent: Friday, April 13, 2018 5:20:40 PM
To: Jakob Ribbing
Cc: Faelens, Ruben (Belgium); nmusers@globomaxnm.com
Subject: Re: [NMusers] ETAs & SIGM
Hi Tingjie,
Assuming (zero and) negative parameter values are not allowed, you could
change from e.g. a linear model to a power model, which is as close as possible
to the linear model, in the range of covariate values from the original
publication.
If the publication lists e.g. median, mean
@Ruben@Jakob Very worthwhile discusstion! I would like to raise an
extended question: if the model contains one covariate, the values of which
from external data make parameters negative, what would be the optimal
solution for this?
@Ruben Out of curiosity, why did you use Nelder-Mead method inst
Hi Ruben,
I think I misread Tingjies original posting as taking ABS(ETA), whereas his
initial attempt was actually ABS(1+ETA), which is less problematic.
The latter would not bias simulations much if IIV is e.g. 30% CV, agreed.
However, as Tingjies is mainly interested in estimation, I believe t
(Belgium)
Sent: maandag 9 april 2018 23:52
To: Tingjie Guo; nmusers@globomaxnm.com
Subject: RE: [NMusers] ETAs & SIGMA in external validation
Hi Tingjie,
A lot of great tips and explanations already. Just wanted to add my two cents.
POSTHOC will estimate the most likely ETA for each individual, ta
Hi Tingjie,
A lot of great tips and explanations already. Just wanted to add my two cents.
POSTHOC will estimate the most likely ETA for each individual, taking into
account the known population parameters THETA and OMEGA. “Most likely” means:
1. An individual parameter as close as possible
Hi Tingjie,
It does not: Sigma squared is the sum of all error variances, and assay error
in most cases is only a small contribution to this sum.
There are exceptions, but when applying a previous model to new data it is
rarely the first modification that comes to my mind.
Given your objectives
Small correction in question 2: *SIGMA* (instead of OMEGA) value influences
individual ETAs...
@Leonid, @Jakob, Thank you both for your input.
@Jakob, You are right, I'm interested in individual ETAs. The idea is to
evaluate the predictive ability of the model in particular subjects
(external da
It would be better to use
$EST METHOD=1 INTERACTION MAXEVAL=0
(at least if the original model was fit with INTERACTION option and
residual error model is not additive).
One option is to use Para = THETA * EXP(ETA)
You would be changing the model, but the model is not too good any way
if you
Dear Tingjie,
If I understand your description correctly, you would like to evaluate the
published model (and point estimates of population parameters) using GoF plots
(residual-error and eta-plots), rather than via simulation (e.g. VPC or PPC)?
At least for the latter it would be necessary to c
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