On Aug 10, 2010, at 11:23 AM, Michal Figurski wrote:
David,
I may have stated my problem incorrectly - my problem is to *obtain
the coordinates* for confidence boundary lines. As input data I have
only CIs for slope and intercept.
Wouldn't you also need to specify the range over which these estimates
might be valid and to offer the means for the X values? What level of
R knowledge are you at? You have provided no data or code. Many R
methods offer predict methods that return CI's.
--
david
rms/Hmisc packages are very nice, but unfortunately they do not work
with Passing-Bablok nor 'nls' models.
--
Michal J. Figurski, PhD
HUP, Pathology & Laboratory Medicine
Biomarker Research Laboratory
3400 Spruce St. 7 Maloney
Philadelphia, PA 19104
tel. (215) 662-3413
W dniu 2010-08-10 11:09, David Winsemius pisze:
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 Winsemius, MD
West Hartford, CT
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