[R] Can't resolve dependency problems with package "sem"

[C&A Säger]

Am 05.05.2016 um 00:17 schrieb Jim Lemon:
> Hi Andreas,
> Try installing plyr, arm, scales and mi separately. If you get an
> error message about a version mismatch, that's where your problem is.
> _Sometimes_ upgrading R will fix it, if the problem is that the
> version you are downloading is too new for your R version.
> 
> Jim
> 

Hello Jim,

Indeed, this might be the problem. When I try to install plyr, I get
something like this:
"Package xxx is not availlable (not for this version 3.0.x)"

I was hoping that any old version from the Ubuntu repositories would be
good enough for an absolute beginner.

Thank you very much,
Andreas