Therneau, Terry M., Ph.D. <therneau <at> mayo.edu> writes: > > > On 12/26/2014 05:00 AM, r-help-request <at> r-project.org wrote: > > i want to analyse survival data using typeI HALF LOGISTIC > > DISTRIBUTION.how can i go about it?it installed one on R in the > > survival package didn't include the distribution...or i need a code to > > use maximum likelihood to estimate the parameter in survival > > analysis.a typical example of distribution other than that installed > > in R will help.thanks > > > I am the author of the survival package, and had never heard of the > "type I half-logistic" before. New distributions can be added to > survreg() if they can be represented as location-scale families; I > don't think that your distribution can be written in that way. Look > at "survival" under the "Task Views" tab (upper left corner) of the > cran.org web page
I don't know about 'type I' but based on http://en.wikipedia.org/wiki/Half-logistic_distribution you could try dhalflogist <- function(x,s,log=FALSE) { r <- log(2)-log(s)-x/s-2*log(1+exp(-x/s)) if (log) r else exp(r) } phalflogist <- function(q,s) { (1-exp(-q/s))/(1+exp(-(q/s))) } rhalflogist <- function(n,s) { abs(rlogis(n,scale=s)) } set.seed(101) rr <- rhalflogist(10000,2) hist(rr,freq=FALSE,breaks=80,col="gray") curve(dhalflogist(x,2),add=TRUE,col=2,lwd=2) d <- data.frame(rr) library("bbmle") m1 <- mle2(rr~dhalflogist(s=exp(logs)),start=list(logs=0),data=d) If you want to fit multiple groups etc., see the 'parameters' argument of ?mle2 ______________________________________________ R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
