[R] Plotting confidence bands around regression line

[Michal Figurski]

Dear R-helpers and graphics gurus,

I have two problems with plotting confidence bands:

1. First is relatively simple. I am using the Passing-Bablok procedure 
to obtain "unbiased" regression coefficients. This procedure yields the 
"a" & "b" coefficient values along with their confidence intervals. I 
then plot the raw data with the regression line, but I would like to add 
the confidence band for the line... and I can't figure out how to do it.

In other words, given:

            Estimate      5%CI     95%CI
Intercept -4.305562 -9.931152 -1.381792
Slope      1.257318  1.053025  1.678516

How to plot the regression line with confidence band?

2. Second problem is plotting confidence bands along fitted "nls" 
regression line. I tried "predict(nls.object, int='c')" - but doesn't 
work. Later I figured in the documentation that the 'int' parameter is 
currently ignored. I guess this means it's not a trivial thing to do. 
Does anyone have a suggestion on how to obtain confidence predictions 
for such a model?

Please cc my email address when you reply. Thanks and best regards,

-- 
Michal J. Figurski, PhD
HUP, Pathology & Laboratory Medicine
Biomarker Research Laboratory
3400 Spruce St. 7 Maloney
Philadelphia, PA 19104
tel. (215) 662-3413