On Mar 23, 2008, at 1:37 PM, Charilaos Skiadas wrote: > panel.points(mean(x), y, col="red", ...) Correction, this should have probably been: panel.points(tapply(x, y, mean), y, col="red", ...) All this assuming you want horizontal boxplots. Haris Skiadas Department of Mathematics and Computer Science Hanover College