Correcting for overdispersion
On Jul 9, 2012, at 20:23 , Lawrence, Adaku wrote:
Hello, I am trying to determine LD50 and LD95 using dose.p in MASS however some of the Residual variance is larger than the degrees of freedom. Please can anyone help with any advice as to how i can correct for this?
Er, in what sense is that a problem? Your code is not reproducible, at least some output to look at might help. -pd
Here is the model as inputted into R y<-cbind(dead,n-dead) model<-glm(y~log(conc),binomial) summary(model) xv<-seq(min(log(conc)-1),max(log(conc)+1),0.01) lines(xv,predict(model,list(conc=exp(xv)),type="response")) dose.p(model,p=c(0.10,0.25,0.5,0.75,0.90,0.95)) Thanks Adaku [[alternative HTML version deleted]]
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Peter Dalgaard, Professor, Center for Statistics, Copenhagen Business School Solbjerg Plads 3, 2000 Frederiksberg, Denmark Phone: (+45)38153501 Email: pd.mes at cbs.dk Priv: PDalgd at gmail.com