orthogonal/perpendicular distance from regression line
Hi Jeff,
You could do this with [1], but if you are hoping to learn something statistical by doing this you should probably reconsider, because the regression line residuals are minimized along the dependent variable axis,
It should be said that there are valid forms of linear regression where this is not true and it is the orthogonal residuals that are wanted. Perhaps the main case is where there are errors in x and y: indeed, this is how the "lines" (i.e. principal components) are fitted in principal component analysis. Regards, Mark.
Jeff Newmiller wrote:
On Fri, 20 Feb 2009, GAF wrote:
Hi there, I am trying to measure orthogonal/perpendicular distances from regression lines (i.e. the shortest distance from a given point to my regression line). As it sounds rather easy (basically just an orthogonal/perpendicular residual) I hoped that there was some function in R that can do that. All efforts so far remained unsuccessful, however. Does anybody know?
You could do this with [1], but if you are hoping to learn something statistical by doing this you should probably reconsider, because the regression line residuals are minimized along the dependent variable axis, and if the coordinate system is rotated (that is, you look at deviation from the regression line to the points along a different direction) then the residuals on that regression line will no longer be minimized. [1] http://mathworld.wolfram.com/Point-LineDistance2-Dimensional.html --------------------------------------------------------------------------- Jeff Newmiller The ..... ..... Go Live... DCN:<jdnewmil at dcn.davis.ca.us> Basics: ##.#. ##.#. Live Go... Live: OO#.. Dead: OO#.. Playing Research Engineer (Solar/Batteries O.O#. #.O#. with /Software/Embedded Controllers) .OO#. .OO#. rocks...2k
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