Here is my primitive and computationally intensive solution to this problem.
Thank you to Michal (see above) for making me aware of the nice polygon
function. I am sure that there are better solutions but this one works for
me at work and for publication.
###
I may be missing something but I don't see how P&B handles errors in
variables any differently than other regression methods that ignore
this problem.
Frank
Frank E Harrell Jr Professor and ChairmanSchool of Medicine
Department of Biostatistics Vanderbilt Uni
>>> Frank Harrell 11/08/2010 17:02:03 >>>
> This problem seems to cry out for one of the many available robust
> regression methods in R.
Not sure that would be much more appropriate, although it would
_appear_ to work. The P&B method is a sort of nonparametric/robust
approach to an errors-in
Frank E Harrell Jr Professor and ChairmanSchool of Medicine
Department of Biostatistics Vanderbilt University
On Wed, 11 Aug 2010, Michal Figurski wrote:
Peter, Frank, David and others,
Thank you all for your ideas. I understand your lack of trust in P&B
meth
Peter, Frank, David and others,
Thank you all for your ideas. I understand your lack of trust in P&B
method. Setting that aside (it's beyond me anyways), please see below
what I have finally came up with to calculate the CI boundaries. Given
the slope and intercept with their 05% & 95% CIs, an
On Aug 10, 2010, at 8:23 PM, Michal Figurski wrote:
> Peter,
>
> Since in P&B the procedure is to calculate a whole list of slopes and
> intercepts, wouldn't it be a solution to determine the correlation and go
> from there? How do I do it?
You can't. (Perhaps someone could, but it looks like
Thanks Michael,
That's the method that Dana Quade taught me in his intro
nonparametrics course at UNC in the mid 1970s, at least for a single
predictor. His method did not incorporate the shift you mentioned
though. The method looks robust. Not sure about efficiency.
Frank
Frank E Harr
Peter,
Since in P&B the procedure is to calculate a whole list of slopes and
intercepts, wouldn't it be a solution to determine the correlation and
go from there? How do I do it?
--
Michal J. Figurski, PhD
HUP, Pathology & Laboratory Medicine
Biomarker Research Laboratory
3400 Spruce St. 7 Ma
Frank,
I had to order this article through Inter-Library Loan and wait for it
for a week!
I'll try to make it short. In Passing-Bablok the principle is to
calculate slopes between all possible pairs of points in the dataset,
and then to take a "shifted" median of those slopes, where the offs
Michal Figurski wrote:
> # And the result of the Passing-Bablok regression on this data frame:
> Estimate 5%CI 95%CI
> Intercept -4.306197 -9.948438 -1.374663
> Slope 1.257584 1.052696 1.679290
>
> The original Passing & Bablok article on this method has an easy
> pre
On Aug 10, 2010, at 12:12 PM, Michal Figurski wrote:
David,
I would consider myself intermediate in R, but a beginner in
statistics. I need a formula that would allow me to calculate
confidence boundaries of the regression line given the slope,
intercept and their CIs (and *any* range).
Please give the prescription. The article is not available on our
extensive online library. I wonder if the method can compete with the
bootstrap.
Frank
Frank E Harrell Jr Professor and ChairmanSchool of Medicine
Department of Biostatistics Vanderbilt Unive
David,
I would consider myself intermediate in R, but a beginner in statistics.
I need a formula that would allow me to calculate confidence boundaries
of the regression line given the slope, intercept and their CIs (and
*any* range).
Passing-Bablok regression doesn't yet exist in R - I am d
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 th
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.
rms/Hmisc packages are very nice, but unfortunately they do not work
with Passing-Bablok nor 'nls' models.
--
Mi
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" &
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 interva
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