NONMEM Users Network Archive

Hosted by Cognigen

RE: change calculation of WRES?

From: R.ter.Heine
Date: Tue, 25 Aug 2009 14:57:07 +0200

Dear Nele,
Couldn't this be solved by simply turning on a flag after a certain time =
and estimate a seperate residual error when this flag is turned on? Ofcou=
rse you can also code this flag in your dataset.


Van: owner-nmusers
amens nele.kaessner
Verzonden: dinsdag 25 augustus 2009 14:21
Aan: nmusers
Onderwerp: [NMusers] change calculation of WRES?

Dear nmusers,

I have a question which I hope is not too trivial for the group. I am cur=
rently analyzing some data where I have more trust in values at late time=
 points. Therefore, I would like WRES to be a function of time, putting=
 more weight on late time points. In the help guide I found that WRES c=
an be influenced by SPTWO, however no real documentation exists (or I am =
not aware of it) about how to use it. Does anybody have an example for me=
 of how to code this?
Moreover, I noticed that no matter how I describe my weighting for IWRES,=
 this does not at all seem to influence my objective function or parame=
ter values. When evaluating a model, most people consider anyway that WR=
ES is what counts, as IWRES are in most cases ok anyway. So my very simpl=
e question is: If this does not influence any of this and I don't use IWR=
ES to decide if a model is good or bad, why bother at all to calculate th=
em? I noticed that the standard errors seem to change depending on which =
weighting I use for IWRES. Can anybody explain this?

Thanks and best wishes

Dr. Nele Kner
Pharmacometrics -- Modeling and Simulation

Nycomed GmbH
Byk-Gulden-Str. 2
D-78467 Konstanz, Germany

Fon: (+49) 7531 / 84 - 4759
Fax: (+49) 7531 / 84 - 94759

mailto: nele.kaessner

County Court: Freiburg, Commercial Register HRB 701257
Chairman Supervisory Board: Charles Depasse
Management Board: Dr. Barthold Piening, Gilbert Rademacher, Dr. Anders Ul=

Proprietary or confidential information belonging to Nycomed Group may
be contained in this message. If you are not the addressee indicated
in this message, please do not copy or deliver this message to anyone.
In such case, please destroy this message and notify the sender by
reply e-mail. Please advise the sender immediately if you or your
employer do not consent to Internet e-mail for messages of this kind.
Opinions, conclusions and other information in this message that
pertain to the sender's employer and its products and services
represent the opinion of the sender and do not necessarily represent
or reflect the views and opinions of the employer.

De informatie in dit e-mail bericht is uitsluitend bestemd
voor de geadresseerde. Verstrekking aan en gebruik door
anderen is niet toegestaan. Door de elektronische verzending
van het bericht kunnen er geen rechten worden ontleend aan de

Received on Tue Aug 25 2009 - 08:57:07 EDT

The NONMEM Users Network is maintained by ICON plc. Requests to subscribe to the network should be sent to:

Once subscribed, you may contribute to the discussion by emailing: