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Ridge Regression variable selection

2 messages · Frank E Harrell Jr, Ben Bolker

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Unlike L1 (lasso) regression or elastic net (mixture of L1 and L2), L2 norm
regression (ridge regression) does not select variables.  Selection of
variables would not work properly, and it's unclear why you would want to
omit "apparently" weak variables anyway.
Frank

maths123 wrote
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Frank Harrell
Department of Biostatistics, Vanderbilt University
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Frank Harrell <f.harrell <at> vanderbilt.edu> writes:
... and this was cross-posted from StackOverflow, where I said more
or less the same thing about ridge regression (I didn't get into the
"don't do variable selection" issue yet, I was waiting ...)

http://stackoverflow.com/questions/14046569/ridge-regression-in-r

  For the other questions (what are the lambda values?  What does
the output mean?) I would suggest getting a copy of _Modern
Applied Statistics in S_ [the book that the package, MASS, was
written to accompany] and reading the relevant chapter.