[R] A beginner's question about ggplot

Dear R-users, I would have another question about the ggplot() function in the ggplot2 package. All the examples I've read so far in the documentation make use of a single neatly formatted data.frame. However, sometimes, one may be interested in plotting on the same grid information or objects d

[R] Overlaying graphs from different datasets with ggplot

Dear R-users, I recently began using the ggplot2 package and I am still in the process of getting used to it. My goal would be to plot on the same grid a number of curves derived from two distinct datasets. The first dataset (called molten.data) looks like this : Column names : Perc, Week, Weig

Re: [R] lme between-group and within-group covariance

structure for the Psi matrix (same notation), that is, a correlation structure for the random effects. If lme() doesn't allow for this, is there any other function that I could use? MUHC-Research wrote: > > Dear R users, > > I would be interested in using the lme() function to

[R] lme between-group and within-group covariance

Dear R users, I would be interested in using the lme() function to fit a linear mixed model to a longitudinal dataset. I know this function allows for the specification of a within-group covariance structure. However, does it allow for the explicit specification of a between-group covariance stru