The October 2006 R News had an article in which the authors discussed a new package that implemented the Birnbaum-Saunders distribution. However, the package (aptly named "bs") does not appear to be available for installation. Does anyone know the status of this package? Thanks. Tom La Bone [[alternative HTML version deleted]]
Hi, the package bs, version 1.0, is available. Yet, I've gote some problems with it, specifically with the maximum likelihood estimation of the parameters \alpha and \beta of Birnbaum-Saunders distribution. Let the following code run: library(bs) alpha<-1.5 beta<-0.5 n<-100 set.seed(1) x<-rbs(n,alpha,beta) est1bs(x) The MLE algorithm does not converge. Not only for this pair of values and for this sample... Please have a look... -- View this message in context: http://r.789695.n4.nabble.com/Status-of-the-bs-Package-tp827806p3033442.html Sent from the R help mailing list archive at Nabble.com.
Perhaps the problem stands on the rbs function which generates random samples from the Birnbaum-Saunders distribution:> library(bs) > set.seed(1) > x<-rbs(n=1000,alpha=0.5,beta=1.0) > # sample mean > mean(x)[1] 1.117749> # expected value > beta*(1+alpha^2/2)[1] 2.125> # so different!-- View this message in context: http://r.789695.n4.nabble.com/Status-of-the-bs-Package-tp827806p3033546.html Sent from the R help mailing list archive at Nabble.com.