Exactly! Thanks, Duncan. Let me re-phrase me question like this:
1) X_i values are independent Gammas, with the shape 0.067 and scale 0.008 2) Min(X)=1 and Max(X)=85 3) SUM(X)=2000 4) Do I also have to define the number of draws? if yes, it could be 250. Based on these restrictions, I want to generate random draw. I'm wondering how I can do this in R. Thanks. Garry On Tue, Nov 10, 2009 at 11:17 AM, Duncan Murdoch <murd...@stats.uwo.ca>wrote: > On 11/10/2009 1:25 PM, Hongwei Dong wrote: > >> Hi, Dear R users, >> >> I'm wondering if I can do Monte Carlo Simulation in R. My problem is like >> this: I know variable X follows Gamma distribution with shape parameter >> 0.067 and scale parameter 0.008. The sum of the X is 2000. I need R help >> me >> to simulate a vector of X that satisfies both the probability distribution >> and the sum. Anyone has a clue to this? Much appreciated. >> > > Your requirements are slightly contradictory or incomplete. Here's one way > to fully specify the problem: > > The X_i values are independent Gammas, with the given shape and scale. You > want to simulate from the joint distribution conditional on the event sum(X) > == 2000. > > Is that your problem? I don't know how to do the simulation, but maybe > someone else does. > > Duncan Murdoch > [[alternative HTML version deleted]] ______________________________________________ R-help@r-project.org 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.