Thank you for your help Abby! On Wed, Dec 16, 2020 at 11:32 PM Abby Spurdle <spurdl...@gmail.com> wrote:
> Hi Chao Liu, > > I'm having difficulty following your question, and examples. > And also, I don't see the motivation for increasing, then decreasing > the sample sizes. > Intuitively, one would compute the correct sample sizes, first time > round... > > But I thought I'd add some comments, just in case they're useful. > > If the problem relates to memberships (in clusters), then the problem > can be simplified. > All one needs is an integer vector, where each value is the index of > the cluster. > > To compute random memberships of 600 observations in 20 clusters, one > could run: > > m <- sample (1:20, 600, TRUE) > > To compute the number of observations per cluster, one could then run: > > table (m) > > In the above code, the probability of an observation being assigned to > each cluster, is uniform. > Non-uniform sampling can be achieved by supplying a 4th argument to > the sample function, which is a numeric vector of weights. > > > On Wed, Dec 16, 2020 at 10:08 PM Chao Liu <psychao...@gmail.com> wrote: > > > > Dear R experts, > > > > I want to simulate some unbalanced clustered data. The number of clusters > > is 20 and the average number of observations is 30. However, I would like > > to create an unbalanced clustered data per cluster where there are 10% > more > > observations than specified (i.e., 33 rather than 30). I then want to > > randomly exclude an appropriate number of observations (i.e., 60) to > arrive > > at the specified average number of observations per cluster (i.e., 30). > The > > probability of excluding an observation within each cluster was not > uniform > > (i.e., some clusters had no cases removed and others had more excluded). > > Therefore in the end I still have 600 observations in total. How to > realize > > that in R? Thank you for your help! > > > > Best, > > > > Liu > > > > [[alternative HTML version deleted]] > > > > ______________________________________________ > > R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see > > 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. > [[alternative HTML version deleted]] ______________________________________________ R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see 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.
