Re: Robust regression

2002-03-01 Thread Rich Ulrich
On 1 Mar 2002 00:36:01 -0800, [EMAIL PROTECTED] (Alex Yu) wrote: I know that robust regression can downweight outliers. Should someone apply robust regression when the data have skewed distributions but do not have outliers? Regression assumptions require normality of residuals

Re: Robust regression

2002-03-01 Thread Vadim and Oxana Marmer
If, for example, normality assumption holds then by doing robust regression instead of OLS you lose efficiency. So, it's not the same result after all. But you can do both, compare and decide. If robust regression produces results which are not really different from the OLS then stay with OLS

Robust regression

2002-02-28 Thread Alex Yu
I know that robust regression can downweight outliers Should someone apply robust regression when the data have skewed distributions but do not have outliers? Regression assumptions require normality of residuals, but not the normality of raw scores So does it help at all to use robust

RE: Robust Regression and Excel for Stats

2002-01-12 Thread Humberto Barreto
= Original Message From Michael Joner [EMAIL PROTECTED] = Does it make a big difference if I use an MM regression, or LTS, or LMS? Good question. I answered your first post from a basic, introductory level. I was trying to convey the idea of robust regression. I used LMS as my

Robust Regression and Excel for Stats

2002-01-11 Thread Humberto Barreto
At 04:00 PM 1/9/02 -0700, Michael Joner wrote: Hi, Can anyone explain on the group or point me to an appropriate website or book which discusses robust regression? Particularly I'm interested in the differences between the MM and LTS robust regressions and a simple linear regression. What

Re: Robust Regression and Excel for Stats

2002-01-11 Thread Shareef Siddeek
Hi Humberto, You have given an excellent simplified account of the usefulness of robust regression and followed it by whole hearted support for Excel uses in Statistics. It looks like you belong to a delta (in mathematical sense) group. Anyway, what do you think about the credibility of Excel

Re: Robust Regression and Excel for Stats

2002-01-11 Thread Michael Joner
Thanks for all the information. Do you know anything about the other variations of robust regression? Does it make a big difference if I use an MM regression, or LTS, or LMS? Mike On 11 Jan 2002 11:07:59 -0800 [EMAIL PROTECTED] (Humberto Barreto) wrote: A book: Rousseeuw, P.J., and Leroy

help: weighted robust regression

2000-11-14 Thread Patrick Agin
Hi, Does someone know how to include weights in the S-Plus rdl1.s algorithm (the robust regression algorithm developed by Hubert Rousseeuw)? Of course, the algorithm already include a weighting scheme (based on distances of x points w.r.t. a robust center of an ellipsoid) but I want, before