Re: [R] Errors in Variables

From: Spencer Graves <spencer.graves_at_pdf.com>
Date: Sun 29 May 2005 - 07:47:19 EST

          I'm sorry, I have not followed this thread, but I wonder if you have considered library(sem), "structural equations modeling"? "Errors in variables" problems are the canonical special case.

          Also, have you done a search of "www.r-project.org" -> search -> "R site search" for terms like "errors in variables regression"? This just led me to "ODRpack", which is NOT a CRAN package but is apparently available after a Google search. If it were my problem, I'd first try to figure out "sem"; if that seemed too difficult, I might then look at "ODRpack".

          Also, have you read the posting guide! http://www.R-project.org/posting-guide.html? This suggests, among other things, that you provide a toy example that a potential respondant could easily copy from your email, test a few modifications, and prase a reply in a minute or so. This also helps clarify your question so any respondants are more likely to suggest something that is actually useful to you. Moreover, many people have reported that they were able to answer their own question in the course of preparing a question for this list using the posting guide.

          hope this helps. spencer graves

Eric-Olivier Le Bigot wrote:

> I'm interested in this "2D line fitting" too! I've been looking,
> without success, in the list of R packages.
>
> It might be possible to implement quite easily some of the formalism
> that you can find in Numerical Recipes (Fortran 77, 2nd ed.), paragraph
> 15.3. As a matter of fact, I did this in R but only for a model of the
> form y ~ x (with a given covariance matrix between x and y). I can send
> you the R code (preliminary version: I wrote it yesterday), if you want.
>
> Another interesting reference might be Am. J. Phys. 60, p. 66 (1992).
> But, again, you would have to implement things by yourself.
>
> All the best,
>
> EOL
>
> --
> Dr. Eric-Olivier LE BIGOT (EOL) CNRS Associate Researcher
> ~~~o~o~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~o~o~~~
> Kastler Brossel Laboratory (LKB) http://www.lkb.ens.fr
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> 4 place Jussieu 75252 Paris CEDEX 05 France
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>
>
> On Wed, 25 May 2005, Jacob van Wyk wrote:
>

>> I hope somebody can help.
>> A student of mine is doing a study on Measurement Error models
>> (errors-in-variables, total least squares, etc.). I have an old
>> reference to a "multi archive"  that contains
>> leiv3: Programs for best line fitting with errors in both coordinates.
>> (The date is October 1989, by B.D. Ripley et al.)
>> I have done a search for something similar in R withour success. Has
>> this been implemented in a R-package, possibly under some sort of
>> assumptions about variances. I would lke my student to apply some
>> regression techniques to data that fit this profile.
>> Any help is much appreciated.
>> (If I have not done my search more carefully - my apologies.)
>> Thanks
>> Jacob
>>
>>
>> Jacob L van Wyk
>> Department of Mathematics and Statistics
>> University of Johannesburg APK
>> P O Box 524
>> Auckland Park 2006
>> South Africa
>> Tel: +27-11-489-3080
>> Fax: +27-11-489-2832
>>
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>
>>

>
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R-help@stat.math.ethz.ch mailing list
https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html Received on Sun May 29 07:53:33 2005

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