[NMusers] time-to-event simulation based diagnostic

[Francois Gaudreault]

Dear NONMEM users

I am currently performing a time-to-event analysis on binary data using a 
weibull distribution (time-varying hazard function).

Using simulation based diagnositcs, I compared `simulated kaplan-Meier` to 
`observed kaplan-Meier`. However, fit looks to good to be true and I was 
actually suspecting a mispecification during the simulation process with PsN


Here is the code used for vpc:

vpc run2.mod -tte=RTTE -flip_comments -samples=100


I used (ICALL.EQ.4) and the flip-comment option in the model file. However, I 
am not sure if I have to generate a new simulation data set (each individual 
having a row for each possible observation time) or use the original one ?

Any advises or comments are welcome

Regards,

-- 





François Gaudreault, Ph.D. Candidate
Pharmacométrie / Pharmacometrics
Chargé de cours / Lecturer
Faculté de pharmacie / Faculty of Pharmacy
Université de Montréal

  

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[Nucci, Gianluca]

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RE: [NMusers] time-to-event simulation based diagnostic

[Mats Karlsson]

Dear Francois,

 

Unless you create a new data set where events are allowed to occur at any
possible time (usually a dense time grid), then the result that you have got
is rather the expected (i.e. too good to be true). 

 

Best regards,

Mats

 

Mats Karlsson, PhD

Professor of Pharmacometrics

 

Dept of Pharmaceutical Biosciences

Faculty of Pharmacy

Uppsala University

Box 591

75124 Uppsala

 

Phone: +46 18 4714105

Fax + 46 18 4714003

 

From: owner-nmus...@globomaxnm.com [mailto:owner-nmus...@globomaxnm.com] On
Behalf Of Francois Gaudreault
Sent: 19 September 2012 22:49
To: nmusers@globomaxnm.com
Subject: [NMusers] time-to-event simulation based diagnostic

 

Dear NONMEM users

I am currently performing a time-to-event analysis on binary data using a
weibull distribution (time-varying hazard function).

Using simulation based diagnositcs, I compared `simulated kaplan-Meier` to
`observed kaplan-Meier`. However, fit looks to good to be true and I was
actually suspecting a mispecification during the simulation process with PsN


Here is the code used for vpc:

vpc run2.mod -tte=RTTE -flip_comments -samples=100


I used (ICALL.EQ.4) and the flip-comment option in the model file. However,
I am not sure if I have to generate a new simulation data set (each
individual having a row for each possible observation time) or use the
original one ?

Any advises or comments are welcome

Regards,

-- 


François Gaudreault, Ph.D. Candidate
Pharmacométrie / Pharmacometrics
Chargé de cours / Lecturer

Faculté de pharmacie / Faculty of Pharmacy
Université de Montréal