If you use lme, you can fit a general correlation structure to the within-subject data, and compare the fit to a model assuming uncorrelated within-subjects errors. That should tell you whether your data are Aren't the G-G and H-F corrections only approximate fixes? Surely it is better to work with a model that actually fits your data, rather than using ad hoc adjustments towards a model that doesn't quite fit. But I'm no psychologist. :-)
Cheers, Simon. On Mon, 2007-06-25 at 08:22 +0200, Peter Dalgaard wrote: > DarrenWeber wrote: > > I'm an experimental psychologist and when I run ANOVA analysis in > > SPSS, I normally ask for a test of non-sphericity (Box's M-test). I > > also ask for output of the corrections for non-sphericity, such as > > Greenhouse-Geisser and Huhn-Feldt. These tests and correction factors > > are commonly used in the journals for experimental and other > > psychology reports. I have been switching from SPSS to R for over a > > year now, but I realize now that I don't have the non-sphericity test > > and correction factors. > > > This can be done using anova.mlm() and mauchly.test() which work on > "mlm" objects, i.e., lm() output where the response is a matrix. There > is no theory, to my knowledge, to support it for general aov() models, > the catch being that you need to have a within-subject covariance matrix. > > ______________________________________________ > 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 > and provide commented, minimal, self-contained, reproducible code. -- Simon Blomberg, BSc (Hons), PhD, MAppStat. Lecturer and Consultant Statistician Faculty of Biological and Chemical Sciences The University of Queensland St. Lucia Queensland 4072 Australia Room 320, Goddard Building (8) T: +61 7 3365 2506 email: S.Blomberg1_at_uq.edu.au The combination of some data and an aching desire for an answer does not ensure that a reasonable answer can be extracted from a given body of data. - John Tukey. ______________________________________________ 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 and provide commented, minimal, self-contained, reproducible code.