hong qin <alongway <at> gmail.com> writes: > > Hi all, > > I have a problem using rdirichlet{gtools}. > For Dir( a1, a2, ..., a_n), its mode can be found at $( a_i -1)/ ( > \sum_{i}a_i - n)$; > The means are $a_i / (\sum_{i} a_i ) $; >
I believe the problem is that the marginal modes are not equal to the full posterior modes. (Think about the two-parameter normal distribution for example; for a sample {x_i}, the mode of the posterior variance is near sum((x_i-\bar x)^2)/n while the marginal mode is near sum((x_i-\bar x)^2)/(n-1) ...) [haven't checked this at all carefully.] Ben Bolker ______________________________________________ R-help@stat.math.ethz.ch 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.