On Wed, 30 Jul 2003, Joerg Schaber wrote: > Hi, > > trying to do a robudt regression of a two-way linear model, I keep > getting the following error: > > > lqs(obs ~ y + s -1,method="lms", contrasts=list(s=("contr.sum"))) > Error: lqs failed: all the samples were singular > > Robust regression with M-estimators works (also regular least square > fits, of course): > rlm.formula(formula = obs ~ y + s - 1, method = "M", contrasts = list(s > = ("contr.sum"))) > > I tried an exact sampling (psamp="exact"), but I keep getting syntax > errors. Any idea how I can make the first one work?
You may well not be able to. lms relies on being able to find a good fit to (just over) 50% of the data. Sounds like you can't fit to 50%. Try increasing `quantile'. Generally resistant methods should be employed with caution for designed experiments (with factor covariates), and your specification of contrasts suggest y is a factor. So this may not make statistical sense either. -- Brian D. Ripley, [EMAIL PROTECTED] Professor of Applied Statistics, http://www.stats.ox.ac.uk/~ripley/ University of Oxford, Tel: +44 1865 272861 (self) 1 South Parks Road, +44 1865 272866 (PA) Oxford OX1 3TG, UK Fax: +44 1865 272595 ______________________________________________ [EMAIL PROTECTED] mailing list https://www.stat.math.ethz.ch/mailman/listinfo/r-help