Hello, I've just located the illuminating explanation by Douglas Bates on degrees of freedom in mixed models. The take-home message appears to be: don't trust the p-values from lme. Questions: Should I give up hypothesis testing for fixed effects terms in mixed models? Has my time spent reading Pinheiro & Bates been in vain? Is there a publication on this issue? Thanks, Dan Bebber Department of Plant Sciences University of Oxford
lmer, p-values and all that
2 messages · Dan Bebber, Simon Blomberg
Try using mcmcsamp() to sample from the posterior distribution of the parameter estimates. You can calculate a p-value from that, if that is your desire. Instructions are in the R wiki: http://wiki.r-project.org/rwiki/doku.php?id=guides:lmer-tests HTH, Simon.
Dan Bebber wrote:
Hello, I've just located the illuminating explanation by Douglas Bates on degrees of freedom in mixed models. The take-home message appears to be: don't trust the p-values from lme. Questions: Should I give up hypothesis testing for fixed effects terms in mixed models? Has my time spent reading Pinheiro & Bates been in vain? Is there a publication on this issue? Thanks, Dan Bebber Department of Plant Sciences University of Oxford
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Simon Blomberg, B.Sc.(Hons.), Ph.D, M.App.Stat. Centre for Resource and Environmental Studies The Australian National University Canberra ACT 0200 Australia T: +61 2 6125 7800 email: Simon.Blomberg_at_anu.edu.au F: +61 2 6125 0757 CRICOS Provider # 00120C 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.