HelponR <suncertain <at> gmail.com> writes: > > Hi, Greg: > > Just let you know that the beta regression package in R can only work for > data on the open interval (0, 1) > > Do you know any good test of mean for beta distribution? How to verify > if the data is beta distributed? > > For example, I may want to test the null : > > mean <= 0.0000000001 > > I think your idea of testing zero for nonnegative numbers makes sense. But > it seems to make a null hypothesis on a distribution, not simply mean. > > I could be bettered off if I can find a good nonparametric test which does > not assume symmetry or a test for beta distribution if the beta > distribution can be verified. > > Many thanks, > > S
Possibly contrary to what the documentation for the beta regression package, the beta distribution has finite density for 0 and 1 _if_ the shape parameters are large enough/variance parameter is small enough (but probably this is not your situation, if you have lots of zeros). fitdistr() in the MASS package will give a maximum-likelihood fit of the beta distribution to a univariate distribution, but if you want to calculate profile confidence limits etc. you might want to look into the mle() function in the stats4 package ... Ben Bolker ______________________________________________ [email protected] mailing list 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.
