[R] recommended computing server for R (March 2009)?
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
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~~~~~~~~~~ - (p.dalgaard at biostat.ku.dk) FAX: (+45) 35327907
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