[R] Plotting confidence bands around regression line
figurski at mail.med.upenn.edu
Tue Aug 10 16:56:09 CEST 2010
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
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