[R] scatterplots: (equal axes and overlay)

[Matthias von Rad]

Hi,
I am doing lots of scatterplots for my dissertation and to make the
comparable, I would like to have equal x- amd - y axis. Can I specify
their scale?
Another question adresses overlay scatterplots. Having prae and post
measures for each case, is it possible to have them in one graph with
symbols or colors for prae and post.
So
scatterplot(bdiprae,mocoprae) and
scatterplot(bdipost,mocopost) in one graph (for example green for prae
and red for post?)
thanks a lot in advance
Matthias