Dotplot error bar caps?

Hi
I've used Dotplot from Hmisc to draw a dotplot with error bars, where each row of the dotplot has two points. Now I'd like for the error bars to have caps on the end so I can see how much they overlap, but I can't figure out how to produce them.

This draws the plot I want, but doesn't add caps:

Dotplot(taxon ~ Cbind(mean, low.error, high.error), groups=treatment, data=jnk.dat, cap=0.015)

I tried varying the value for cap.

I'd greatly appreciate a pointer for this.

Thank you
John Bishop
School of Biological Sciences
Washington State University


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