thank you all.
i have deliberately chosen matinv (although obviously
an outdated version) because it uses the sweep operator.
i know of other methods to calculate generalized inverses.
however, it is also true that the sweep operator is capable of
computing g2 generalized inverses.
The ginv returns the Moore-Penrose inverse, which has nicer
numerical properties if computed by svd, but it is just not
what i want.
(besides, svd is very slow and should not be applied to the normal
equations anyway)
so lets explain my peculiar interest in matinv:
i am trying get my head around the type III SS that
SAS popularized. i know that those hypotheses are
hated in the R community but they are the standard
hypothesis given by all other statistics software.
i know how to compute type III SS and how to translate them
to meaningful hypothesis of the cell means model.
but i do not have an intuitive understanding why
they are computed as they are.
so i came across my matinv problem when i tried to
to compute the generating matrix
_
H = (X'X) X'X
used for the construction of estimable functions.
if the g2-inverse is used, then H has canonical form
which simpifies the interpretion.
i just wanted to check if it is invariant to cell frequencies.
--
View this message in context:
http://r.789695.n4.nabble.com/generalized-inverse-using-matinv-Design-tp3747337p3749373.html
Sent from the R help mailing list archive at Nabble.com.
______________________________________________
R-help@r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
