rgamma question
On Thu, 5 Feb 2004, Icabalceta, Jorge L. wrote:
I was trying to generate random numbers with a gamma distribution. In R the function is: rgamma(n, shape, rate = 1, scale = 1/rate). My question is that if X~gamma(alpha, beta) and I want to generate one random number where do I plug alpha and beta in rgamma? and, what is the meaning and use of rate?
It depends on what you mean by gamma(alpha,beta). It could be rgamma(1,alpha,beta) or rgamma(1,alpha,1/beta) since both of these parameterisations are used. If you think the mean of gamma(alpha,beta) is alpha*beta, use the second one, if you think it is alpha/beta use the first one. -thomas