[R] Plotting confidence bands around regression line

[David Winsemius]

On Aug 10, 2010, at 10:56 AM, Michal Figurski wrote:

> 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?

Take a look at plotCI in either gplots or plotrix packages.

Harrell's rms/Hmisc packages are nicely integrated with lattice and  
encourage you to create effective displays of models that remove  
simplistic linearity assumptions.

-- 
David.

>
> 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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David Winsemius, MD
West Hartford, CT