Dear list, I have encountered a special case for searching a linear regression where I'm not satisfied with the results obtained using the traditional least squares method (sometimes called OLS) for estimating/optimizing the residues to the regression line (see code below). Basically, a group of my x-y data are a bit off the diagonal line (in my case the diagonal represents the ideal or theoretical fit between x and y, which are in the same scale) and thus these points have sufficient power to impose a slope deviating (too much) from the diagonal. Using rlm() didn't help since this is not a problem of rare outliers. From a pragmatic point of view using a linear regression approach does fit very well the nature of the data & comparison I'd like to perform, so that's why I'd like to stay with something linear.
Has anybody already implemented a function or package in R allowing to modify the exponent (of the least squares method) or more general allowing to define the model to be used for estimating/optimizing the residues ? Thank's in advance Wolfgang Raffelsberger > plot(x,y) # x and y are my data > regr <- lm(y~x) > abline(regr) > # I'm not satisfied with the line since there is one group of points following very well the diagonal but the regression is deviated by another group of points ... > > sessionInfo() R version 2.6.0 (2007-10-03) i386-pc-mingw32 locale: LC_COLLATE=French_France.1252;LC_CTYPE=French_France.1252;LC_MONETARY=French_France.1252;LC_NUMERIC=C;LC_TIME=French_France.1252 attached base packages: [1] stats graphics grDevices datasets tcltk utils methods [8] base other attached packages: [1] svSocket_0.9-5 svIO_0.9-5 R2HTML_1.58 svMisc_0.9-5 svIDE_0.9-5 loaded via a namespace (and not attached): [1] tools_2.6.0 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Wolfgang Raffelsberger, PhD Laboratoire de BioInformatique et Génomique Intégratives CNRS UMR7104, IGBMC 1 rue Laurent Fries, 67404 Illkirch Strasbourg, France Tel (+33) 388 65 3300 Fax (+33) 388 65 3276 [EMAIL PROTECTED] ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
