Thanks, Greg. I think you are right. I did simulation one right after the other, less than 2 seconds.
But still, it was shocking to see identical samples, which I had to throw away. As a rule of thumb, should I do simulation in one R console, rather than splitting the work into 2 consoles. I just thought it would take less time for me, but it seems risky. Thanks, Mike On Wed, Feb 20, 2013 at 6:13 PM, Greg Snow <538...@gmail.com> wrote: > To know for sure we need to know how you are running these different R > sessions, but here are some possibilities: > > The help page for "set.seed" says that if no seed exists then the seed is > set based on the current time (and since 2.14.0 the process ID). So one > possibility is that 2 of the sessions are started close enough together > that they get the same seed. Or the difference in time and process ID > cancel each other out. > > Another possibility (also mentioned in the help page) is that if the seed > was saved in a previous session then it will be restored in the new > session, if all the sessions are reading in the same stored session (or > just the 2 that are the same) then they would start from the same seed. > > > On Tue, Feb 19, 2013 at 6:31 PM, C W <tmrs...@gmail.com> wrote: > >> Hi, list >> I am doing 100,000 iterations of Bayesian simulations. >> >> What I did is I split it into 4 different R sessions, each one runs 25,000 >> iteration. But two of the sessions gave the simulation result. >> >> I did not use any set.seed(). What is going on here? >> >> Thanks, >> Mike >> >> [[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. >> > > > > -- > Gregory (Greg) L. Snow Ph.D. > 538...@gmail.com > [[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.
