Dear R users I have been looking for functions that can deal with overdispersed poisson models. According to actuarial literature (England & Verall, Stochastic Claims Reserving in General Insurance , Institute of Actiuaries 2002) this can be handled through the use of quasi likelihoods instead of normal likelihoods. However, we see them frequently in this type of data, and we would like to be able to fit the model anyway. If it is possible, would you please show me how to find the corresponding package and utilize them? Best Regards, Chi Kai
You can use glm to analysis this data ,with family=quasipoisson. see ?glm and ?family 2006/7/10, g0354502 <g0354502 at nccu.edu.tw>:> Dear R users > > I have been looking for functions that can deal with overdispersed poisson > models. According to actuarial literature (England & Verall, Stochastic Claims > Reserving in General Insurance , Institute of Actiuaries 2002) this can be handled through the > use of quasi likelihoods instead of normal likelihoods. However, we see them frequently > in this type of data, and we would like to be able to fit the model anyway. > If it is possible, would you please show me how to find the corresponding package and utilize them? > > Best Regards, > > Chi Kai > > > > ______________________________________________ > 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 > >-- ?????? Department of Sociology Fudan University
Dear Chi Kai, Three years ago there was a similar thread. At that time David Firth offered a solution for the quasipoission problem with negative observations, see: http://finzi.psych.upenn.edu/R/Rhelp02a/archive/16143.html I remember that his code gave you slightly different answers than the example in England and Verrall's paper. Kind Regards Markus Gesmann FPMA Lloyd's Market Analysis Lloyd's * One Lime Street * London * EC3M 7HA Telephone +44 (0)20 7327 6472 Facsimile +44 (0)20 7327 5718 http://www.lloyds.com -----Original Message----- From: r-help-bounces at stat.math.ethz.ch [mailto:r-help-bounces at stat.math.ethz.ch] On Behalf Of g0354502 Sent: 10 July 2006 05:26 To: r-help at stat.math.ethz.ch Subject: [R] about overdispersed poisson model Dear R users I have been looking for functions that can deal with overdispersed poisson models. According to actuarial literature (England & Verall, Stochastic Claims Reserving in General Insurance , Institute of Actiuaries 2002) this can be handled through the use of quasi likelihoods instead of normal likelihoods. However, we see them frequently in this type of data, and we would like to be able to fit the model anyway. If it is possible, would you please show me how to find the corresponding package and utilize them? Best Regards, Chi Kai ********************************************************************** The information in this E-Mail and in any attachments is CON...{{dropped}}