Dieter Menne [EMAIL PROTECTED] writes:
Andreas Cordes andreas.cordes at stud.uni-goettingen.de writes:
Hi,
I would like to fit a model for a factorial design that allows for
unequal variances in all groups. If I am not mistaken, this can be done
in lm by specifying weights.
A function intended to specify weights for unequal variance structures
is provided in the nlme library with the varIdent function. Is it
apropriate to use these weights with lm? If not, is there another
possibility to do factorial designs with heteroscedasticity?
No, varIdent and friends is made for use with mixed effect models in package
nlme.
- or with generalized least squares, using the gls() function in the same
package.
--
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
~~ - ([EMAIL PROTECTED]) FAX: (+45) 35327907
__
R-help@stat.math.ethz.ch mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
