[R] recommended computing server for R (March 2009)?

Peter Dalgaard p.dalgaard at biostat.ku.dk
Sat Mar 28 17:47:26 CET 2009

Douglas Bates wrote:

> You could use the LAPACK = TRUE argument to R's qr function to get the
> unconstrained pivoting scheme and use that to get coefficient
> estimates according to the estimated rank of the model matrix (see
> example(qr)) but that won't give you the information needed for the
> analysis of variance decompositions.

Yup. However, my gut feeling is that there could be a way out:

First, how important are (sequential) ANOVA decompositions anyway; and 
secondly, is it crucial that they can be read directly off the QR 
decomposition? There's a lot of code that assumes that this is the case, 
so you can't _easily_ plug in a pivoting QR, but the ANOVA can obviously 
be obtained by other means - basically just fit the relevant sequence of 
models and look at the SSD differences (as I suppose glm() must already 
do for deviance tables).

    O__  ---- Peter Dalgaard             Øster Farimagsgade 5, Entr.B
   c/ /'_ --- Dept. of Biostatistics     PO Box 2099, 1014 Cph. K
  (*) \(*) -- University of Copenhagen   Denmark      Ph:  (+45) 35327918
~~~~~~~~~~ - (p.dalgaard at biostat.ku.dk)              FAX: (+45) 35327907

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