I was now preparing to try to implement the LASSO via Least Angle Regression, but in order to do it I have to prove first that all its nice properties are still valid when minimizing instead of . So far, I haven't seen any work that actually does all this, but some time ago I also read a quote that said something like "those who don't know statistics are doomed to rediscover it" (by Brad Efron, perhaps?), so that's why I'm asking here first (given that I'm a relative newcomer to the statistics literature): is this already done somewhere for these models? Is it implemented in R in some way? (including the solution and implementation of the ridge by minimizing instead of , which is what's implemented in the lm.ridge code in R)?
Thanks in advance for your answers!
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Antworten:
If we know the Cholesky decompositionV−1=LTL , say, then
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