Hi everybody,
we are a pool of phd students and we have a question about AIC. We are interested
in calculating the AIC for a mixture model on galaxies data. So far we have
found AIC works only for regression models, whereas we need AIC for a mixture
of Normal with mean, sd and weights given by our EM algorithm.
May you help us?
thanks in advance
__________________________________________________________________
Tiscali Adsl 2 Mega Free: naviga gratis tutto l'anno!
Supera tutti i limiti di velocita' con Tiscali Adsl 2 Mega Free.
Sei libero da costi fissi e, se ti abboni entro il 25 novembre,
navighi gratis fino al 31 dicembre 2004 e non paghi il costo di adesione.
http://abbonati.tiscali.it/adsl/
question about AIC
4 messages · dlavecchia@tiscali.it, Brian Ripley, Dimitris Rizopoulos +1 more
On Tue, 16 Nov 2004 dlavecchia at tiscali.it wrote:
we are a pool of phd students and we have a question about AIC. We are interested in calculating the AIC for a mixture model on galaxies data. So far we have found AIC works only for regression models, whereas we need AIC for a mixture of Normal with mean, sd and weights given by our EM algorithm.
What is the problem? The concept AIC or the function AIC()? If the concept, it was originally developed in the area of AR(p) time series models, using asymptotic theory for MLEs, and you need to check that the concepts apply to your situation (the original papers do not). Note there are some fundamental problems here: the likelihood for a mixture of normals is unbounded, the MLE corresponding to degenerate (zero-variance) components. And AIC is about maximized likelihoods, with maxima in the interior of the space. So you need to take some professional statistical advice about the concepts.
Brian D. Ripley, ripley at stats.ox.ac.uk Professor of Applied Statistics, http://www.stats.ox.ac.uk/~ripley/ University of Oxford, Tel: +44 1865 272861 (self) 1 South Parks Road, +44 1865 272866 (PA) Oxford OX1 3TG, UK Fax: +44 1865 272595
did you try google? e.g., with key word: `AIC mixture models'. Moreover, look at package `flexmix' (i.e., help(package="flexmix")) whose usage is illustrated in a recent article in JSS: http://www.jstatsoft.org/v11/i08/v11i08.pdf I hope it helps. Best, Dimitris ---- Dimitris Rizopoulos Ph.D. Student Biostatistical Centre School of Public Health Catholic University of Leuven Address: Kapucijnenvoer 35, Leuven, Belgium Tel: +32/16/396887 Fax: +32/16/337015 Web: http://www.med.kuleuven.ac.be/biostat http://www.student.kuleuven.ac.be/~m0390867/dimitris.htm ----- Original Message ----- From: <dlavecchia at tiscali.it> To: <R-help at stat.math.ethz.ch> Sent: Tuesday, November 16, 2004 10:12 AM Subject: [R] question about AIC
Hi everybody, we are a pool of phd students and we have a question about AIC. We are interested in calculating the AIC for a mixture model on galaxies data. So far we have found AIC works only for regression models, whereas we need AIC for a mixture of Normal with mean, sd and weights given by our EM algorithm. May you help us? thanks in advance
__________________________________________________________________ Tiscali Adsl 2 Mega Free: naviga gratis tutto l'anno! Supera tutti i limiti di velocita' con Tiscali Adsl 2 Mega Free. Sei libero da costi fissi e, se ti abboni entro il 25 novembre, navighi gratis fino al 31 dicembre 2004 e non paghi il costo di adesione. http://abbonati.tiscali.it/adsl/ ______________________________________________ R-help at stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
I would also mention the "mixreg" package on CRAN. Regards m. ********************************************** Massimiliano Marinucci http://personales.ya.com/max_mar/ Ph.D Candidate in Economics Fundamentos del Analisis Econ??mico II (Econom??a Cuantitativa) Facultad de CC.EE. Universidad Complutense Madrid Campus de Somosaguas Madrid - Spain ********************************************** ----- Original Message ----- From: "Dimitris Rizopoulos" <dimitris.rizopoulos at med.kuleuven.ac.be> To: <dlavecchia at tiscali.it> Cc: <r-help at stat.math.ethz.ch> Sent: Tuesday, November 16, 2004 10:35 AM Subject: Re: [R] question about AIC
did you try google? e.g., with key word: `AIC mixture models'. Moreover, look at package `flexmix' (i.e., help(package="flexmix")) whose usage is illustrated in a recent article in JSS: http://www.jstatsoft.org/v11/i08/v11i08.pdf I hope it helps. Best, Dimitris ---- Dimitris Rizopoulos Ph.D. Student Biostatistical Centre School of Public Health Catholic University of Leuven Address: Kapucijnenvoer 35, Leuven, Belgium Tel: +32/16/396887 Fax: +32/16/337015 Web: http://www.med.kuleuven.ac.be/biostat http://www.student.kuleuven.ac.be/~m0390867/dimitris.htm ----- Original Message ----- From: <dlavecchia at tiscali.it> To: <R-help at stat.math.ethz.ch> Sent: Tuesday, November 16, 2004 10:12 AM Subject: [R] question about AIC
Hi everybody, we are a pool of phd students and we have a question about AIC. We are interested in calculating the AIC for a mixture model on galaxies data. So far we have found AIC works only for regression models, whereas we need AIC for a mixture of Normal with mean, sd and weights given by our EM algorithm. May you help us? thanks in advance
__________________________________________________________________ Tiscali Adsl 2 Mega Free: naviga gratis tutto l'anno! Supera tutti i limiti di velocita' con Tiscali Adsl 2 Mega Free. Sei libero da costi fissi e, se ti abboni entro il 25 novembre, navighi gratis fino al 31 dicembre 2004 e non paghi il costo di adesione. http://abbonati.tiscali.it/adsl/ ______________________________________________ R-help at stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
______________________________________________ R-help at stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide!
http://www.R-project.org/posting-guide.html