Re: [R] Under-dispersion - a stats question?

2005-10-12 Thread Martin Henry H. Stevens
Hello all: Thank you for you interest. This text of this email is in the attached "R-help.r" file. The R script is in "R-helpscript.r". The data set is "wk6trial.csv". One of my students has performed a laboratory experiment with petri dishes containing hundreds of species of bacteria, and

Re: [R] Under-dispersion - a stats question?

2005-10-11 Thread Jari Oksanen
On Tue, 2005-10-11 at 17:16 -0400, Kjetil Holuerson wrote: > Martin Henry H. Stevens wrote: > > Hello all: > > I frequently have glm models in which the residual variance is much > > lower than the residual degrees of freedom (e.g. Res.Dev=30.5, Res.DF > > = 82). Is it appropriate for me to use

Re: [R] Under-dispersion - a stats question?

2005-10-11 Thread Prof Brian Ripley
On Mon, 10 Oct 2005, Martin Henry H. Stevens wrote: > Hello all: > I frequently have glm models in which the residual variance is much > lower than the residual degrees of freedom (e.g. Res.Dev=30.5, Res.DF > = 82). Is it appropriate for me to use a quasipoisson error > distribution and test it wi

Re: [R] Under-dispersion - a stats question?

2005-10-11 Thread Kjetil Holuerson
Martin Henry H. Stevens wrote: > Hello all: > I frequently have glm models in which the residual variance is much > lower than the residual degrees of freedom (e.g. Res.Dev=30.5, Res.DF > = 82). Is it appropriate for me to use a quasipoisson error > distribution and test it with an F distribu

Re: [R] Under-dispersion - a stats question?

2005-10-10 Thread Peter Dalgaard
"Martin Henry H. Stevens" <[EMAIL PROTECTED]> writes: > Hello all: > I frequently have glm models in which the residual variance is much > lower than the residual degrees of freedom (e.g. Res.Dev=30.5, Res.DF > = 82). Is it appropriate for me to use a quasipoisson error > distribution and te

[R] Under-dispersion - a stats question?

2005-10-10 Thread Martin Henry H. Stevens
Hello all: I frequently have glm models in which the residual variance is much lower than the residual degrees of freedom (e.g. Res.Dev=30.5, Res.DF = 82). Is it appropriate for me to use a quasipoisson error distribution and test it with an F distribution? It seems to me that I could stand