[R] Piece-wise continuous regression with one knot

Achim Zeileis Achim.Zeileis at uibk.ac.at
Thu Dec 23 15:09:17 CET 2010

On Thu, 23 Dec 2010, John Sorkin wrote:

> Windows Vista
> R 2.10 - I know it is old, I will update later today.
> How might I perform a piece-wise linear regression where two linear 
> segments are separated by a single knot? In addition to estimating the 
> slopes of the two segments (or the slope in one segment and the 
> difference between the slope of the first and second segment), I would 
> like the analysis to select the optimum knot. My first analysis will 
> contain a single dependent and a single independent variables. 
> Subsequent analyses will add additional independent variables to 
> determine the effect on the results of adjusting for potential 
> confounding.

Have a look at the "segmented" package, introduced in R News in


> Thank you,
> John
> John David Sorkin M.D., Ph.D.
> Chief, Biostatistics and Informatics
> University of Maryland School of Medicine Division of Gerontology
> Baltimore VA Medical Center
> 10 North Greene Street
> GRECC (BT/18/GR)
> Baltimore, MD 21201-1524
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> (Fax) 410-605-7913 (Please call phone number above prior to faxing)
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