Re: [NMusers] Mixture model with logistic regression

2016-02-20 Thread Mark Sale
mittal. From: Jeroen Elassaiss-Schaap (PD-value B.V.) Sent: Saturday, February 20, 2016 4:35 PM To: Mark Sale Cc: nmusers@globomaxnm.com Subject: Re: [NMusers] Mixture model with logistic regression Hi Mark, Is it indeed a logistical model or is it an ordered categorical? I assu

Re: [NMusers] Mixture model with logistic regression

2016-02-20 Thread Gerry Sheng
Hi Mark, My first suggestion is you can start from simpler mixture model (e.g. 2 distributions) and only focus on those have AEs. 68% patients without AE is a big disturbance to intercept. Only negative infinity of intercept in logistic model can give a probability=0. Secondly, you can try to use

Re: [NMusers] Mixture model with logistic regression

2016-02-20 Thread Jeroen Elassaiss-Schaap (PD-value B.V.)
*Sent:* Saturday, February 20, 2016 2:44 PM *To:* Mark Sale *Cc:* nmusers@globomaxnm.com *Subject:* Re: [NMusers] Mixture model with logistic regression Hi Mark, The pattern you see in the posthocs could possibly be a shrinkage phenomenon. I.e. patients with AE most of the time will have the same ETA

Re: [NMusers] Mixture model with logistic regression

2016-02-20 Thread Mark Sale
Cc: nmusers@globomaxnm.com Subject: Re: [NMusers] Mixture model with logistic regression Hi Mark, The pattern you see in the posthocs could possibly be a shrinkage phenomenon. I.e. patients with AE most of the time will have the same ETA, while patients with no AE will have the same ETA and there will be a

Re: [NMusers] Mixture model with logistic regression

2016-02-20 Thread Matts Kågedal
Hi Mark, The pattern you see in the posthocs could possibly be a shrinkage phenomenon. I.e. patients with AE most of the time will have the same ETA, while patients with no AE will have the same ETA and there will be a third group in between. If shrinkage is causing this, you should not expect any

[NMusers] Mixture model with logistic regression

2016-02-19 Thread Mark Sale
Has anyone every tried to use a mixture model with logistic regression? I have data on a AE in several hundred patients, measured multiple times (10-20 times per patient). Examining the data it is clear that, independent of drug concentration, there is very wide distribution of this AE, 68% of

Re: [NMusers] Mixture model simulation

2013-05-07 Thread Paul Hutson
ox 591 75124 Uppsala Phone: +46 18 4714105 Fax + 46 18 4714003 -Original Message- From: owner-nmus...@globomaxnm.com [mailto:owner-nmus...@globomaxnm.com] On Behalf Of Paul Hutson Sent: 07 May 2013 17:32 To: nmusers@globomaxnm.com Subject: [NMusers] Mixture model simulation Dear Users: I n

RE: [NMusers] Mixture model simulation

2013-05-07 Thread E.Olofsen
ht be different for the subgroups? Erik From: owner-nmus...@globomaxnm.com [owner-nmus...@globomaxnm.com] on behalf of Paul Hutson [prhut...@pharmacy.wisc.edu] Sent: Tuesday, May 07, 2013 5:31 PM To: nmusers@globomaxnm.com Subject: [NMusers] Mixture

RE: [NMusers] Mixture model simulation

2013-05-07 Thread Mats Karlsson
aul Hutson Sent: 07 May 2013 17:32 To: nmusers@globomaxnm.com Subject: [NMusers] Mixture model simulation Dear Users: I note the Jan 26, 2013 response to Nick Holford's query about results from the use of the $MIX mixture model for simulation. I have created a data set of N=100 subjects usin

Re: [NMusers] Mixture model simulation

2013-05-07 Thread Leonid Gibiansky
Well, it was the wrong guess, MIXNUM should work -- Leonid Gibiansky, Ph.D. President, QuantPharm LLC web:www.quantpharm.com e-mail: LGibiansky at quantpharm.com tel:(301) 767 5566 should it be IF(MIXEST.EQ.2) Z=0 for the fitting run? On 5/7/2013 1

Re: [NMusers] Mixture model simulation

2013-05-07 Thread Leonid Gibiansky
should it be IF(MIXEST.EQ.2) Z=0 for the fitting run? -- Leonid Gibiansky, Ph.D. President, QuantPharm LLC web:www.quantpharm.com e-mail: LGibiansky at quantpharm.com tel:(301) 767 5566 On 5/7/2013 11:31 AM, Paul Hutson wrote: Dear Users: I note t

[NMusers] Mixture model simulation

2013-05-07 Thread Paul Hutson
Dear Users: I note the Jan 26, 2013 response to Nick Holford's query about results from the use of the $MIX mixture model for simulation. I have created a data set of N=100 subjects using R to randomly distribute their covariates, both continuous and categorical. I then ran the following sim

RE: [NMusers] Mixture model simulation

2013-01-25 Thread Bauer, Robert
sage- From: owner-nmus...@globomaxnm.com [mailto:owner-nmus...@globomaxnm.com] On Behalf Of Nick Holford Sent: Friday, January 25, 2013 4:00 PM To: nmusers Subject: Re: [NMusers] Mixture model simulation Tom (and others), Thanks for your replies and suggestions. I've looked at the behaviour

RE: [NMusers] Mixture model simulation

2013-01-25 Thread E.Olofsen
[n.holf...@auckland.ac.nz] Sent: Friday, January 25, 2013 10:00 PM To: nmusers Subject: Re: [NMusers] Mixture model simulation Tom (and others), Thanks for your replies and suggestions. I've looked at the behaviour of both MIXNUM and MIXEST. As Tom stated it seems that MIXNUM describe

Re: [NMusers] Mixture model simulation

2013-01-25 Thread Nick Holford
I am not certain what value MIXEST will have for each individual. Best wishes, Tom Ludden -Original Message- From: owner-nmus...@globomaxnm.com [mailto:owner-nmus...@globomaxnm.com] On Behalf Of Nick Holford Sent: Friday, January 25, 2013 2:51 AM To: nmusers Subject: [NMusers] Mixture

R: [NMusers] Mixture model simulation

2013-01-25 Thread Roberto Gomeni
...@globomaxnm.com] Per conto di Nick Holford Inviato: venerdì 25 gennaio 2013 09:51 A: nmusers Oggetto: [NMusers] Mixture model simulation Hi, I've been puzzled by the behaviour of NONMEM when trying to simulate with a mixture model. The data file has 1000 subjects. I simulate 100 times (see control s

RE: [NMusers] Mixture model simulation

2013-01-25 Thread E.Olofsen
, 2013 9:50 AM To: nmusers Subject: [NMusers] Mixture model simulation Hi, I've been puzzled by the behaviour of NONMEM when trying to simulate with a mixture model. The data file has 1000 subjects. I simulate 100 times (see control stream below). The overall number of subjects with MIXEST of 1

[NMusers] Mixture model simulation

2013-01-25 Thread Nick Holford
Hi, I've been puzzled by the behaviour of NONMEM when trying to simulate with a mixture model. The data file has 1000 subjects. I simulate 100 times (see control stream below). The overall number of subjects with MIXEST of 1 is 45%. There are no simulated values of 99. All values are either 1

RE: [NMusers] Mixture model

2012-07-12 Thread Gobburu, Joga
ryland.edu<mailto:ctm-unsubscr...@lists.umaryland.edu> From: owner-nmus...@globomaxnm.com [mailto:owner-nmus...@globomaxnm.com] On Behalf Of Fisher Dennis Sent: Thursday, July 12, 2012 4:25 PM To: nmusers@globomaxnm.com Subject: [NMusers] Mixture model Colleagues I am analyzing data in w

[NMusers] Mixture model

2012-07-12 Thread Fisher Dennis
Colleagues I am analyzing data in which there are two distinct populations as a result of CYP2D6 deficiency. In one dataset, there are 18 subjects with rich data; one of these subjects is markedly different. In that the incidence of 2D6 deficiency is reported to be < 10%, one would expect onl

Re: [NMusers] mixture model coding

2012-05-05 Thread Nick Holford
Gaurav, Some suggestions: 1. I cannot see how you are introducing treatment into the model. You have something that is a function of time (EFF1) but not of treatment. I'd suggest including whether treatment is being used or not (statistical/regulatory view from a dark cave) or a function of d

[NMusers] mixture model coding

2012-05-05 Thread Gaurav Bajaj
Dear All, I am trying to model a tumor size data at different time points using NONMEM. There is high variability in baseline tumor size and their might be sub-populations in the dataset with different distribution for size progression. For example, in many cases the baseline tumor size is aroun

Re: [NMusers] Mixture model for Disease Progression

2011-01-16 Thread indrajeet singh
.2) Q2=1 ; PDT IS 2 FOR BIOMARKER > > > > Y=Q1*Y1+Q2*Y2 > > > > $MIX > > NSPOP=2 > > P(1)=THETA(11) ;PATHOLOGIC > > P(2)=1-THETA(11) ;NON-PATHOLOGIC > > > > $THETA > > ... > > (0,FIX) ;THETA(8) FIXED TO ZERO FOR NON PROGRESSERS > &

RE: [NMusers] Mixture model for Disease Progression

2011-01-16 Thread Samtani, Mahesh [PRDUS]
R NON PROGRESSERS ... $OMEGA 1 FIX 1 FIX $SIGMA 1 FIX 1 FIX From: owner-nmus...@globomaxnm.com on behalf of Nick Holford Sent: Sun 1/16/2011 1:49 AM To: nmusers@globomaxnm.com Subject: Re: [NMusers] Mixture model for Disease Progression Mahesh

Re: [NMusers] Mixture model for Disease Progression

2011-01-15 Thread Nick Holford
Mahesh, Do you have a good biological reason to divide your population into different subpopulations? If not then a more flexible way to describe an association between baseline and slope is estimate the covariance between the random effects. This does carry with it the explicit assumption t

[NMusers] Mixture model for Disease Progression

2011-01-14 Thread Samtani, Mahesh [PRDUS]
Hello, I am trying some simple linear disease progression analysis and the data suggests that there are 2 populations in the dataset (Low Baseline, Low Slope vs. High Baseline, High Slope). It appears that that population consists of progressers and non-progressers (The Pharmacometrics textbook de