On Mon, 2006-09-11 at 11:43 -0500, Douglas Bates wrote: > On 9/10/06, Andrew Robinson <[EMAIL PROTECTED]> wrote: > > On Thu, Sep 07, 2006 at 07:59:58AM -0500, Douglas Bates wrote: > > > > > I would be happy to re-institute p-values for fixed effects in the > > > summary and anova methods for lmer objects using a denominator degrees > > > of freedom based on the trace of the hat matrix or the rank of Z:X if > > > others will volunteer to respond to the "these answers are obviously > > > wrong because they don't agree with <whatever> and the idiot who wrote > > > this software should be thrashed to within an inch of his life" > > > messages. I don't have the patience. > > > > This seems to be more than fair to me. I'll volunteer to help explain > > why the anova.lmer() output doesn't match SAS, etc. Is it worth > > putting a caveat in the output and the help files? Is it even worth > > writing a FAQ about this? > > Having made that offer I think I will now withdraw it. Peter's > example has convinced me that this is the wrong thing to do. > > I am encouraged by the fact that the results from mcmcsamp correspond > closely to the correct theoretical results in the case that Peter > described. I appreciate that some users will find it difficult to > work with a MCMC sample (or to convince editors to accept results > based on such a sample) but I think that these results indicate that > it is better to go after the marginal distribution of the fixed > effects estimates (which is what is being approximated by the MCMC > sample - up to Bayesian/frequentist philosophical differences) than to > use the conditional distribution and somehow try to adjust the > reference distribution.
Am I right that the MCMC sample can not be used, however, to evaluate the significance of parameter groups. For example, to assess the significance of a three-level factor? Are there better alternatives than simply adjusting the CI for the number of factor levels (1-alpha/levels). Thanks! Manuel = Manuel A. Morales Asst. Prof., Biology Williams College http://mutualism.williams.edu ______________________________________________ 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.