Please read this first: http://www.perceptualedge.com/articles/visual_business_intelligence/dual-scaled_axes.pdf
It's a reasoned discussion of why it's a bad idea and proposes some alternative methods. Another good article is: K. W. Haemer. Double scales are dangerous. The American Statistician, 2(3):24–24, 1948. People have been advising dual-axis plots for (at least) 60 years! Hadley -- http://had.co.nz/ ______________________________________________ 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.
