lme4 mcmcsamp matrix not PD
Hi folks, A follow up - this problem happens only stochastically. Further, a little trial and error indicates that using mathod="Laplace" or method="AGQ" reduces the frequency of the problem. Why? I have no idea, and even this could be my own wishful interpretation of my trial and error. -Hank
On Dec 20, 2006, at 4:20 PM, Martin Henry H. Stevens wrote:
Hi folks, I am not providing a small replicable example, because I assume the problem is related to my quirky data (~650 obs.). I am using the latest lme4, matrix and coda, and R 2.4.0. I frequently get the following error message for this particular lmer model. I do not get this message for the vast majority of my uses of mcmcsamp. I was wondering if it might be characteristic of particular kinds of problems.
modb <- lmer(log(basal+1) ~ nutrient*amd + (1|rack) + (1|
gen:amd), data=dat.b2)
mod.mc <- mcmcsamp(modb, n=10^4)
Error: Matrix is not pd after safe_pd_matrix! Error in t(.Call(mer_MCMCsamp, object, saveb, n, trans, verbose)) : error in evaluating the argument 'x' in selecting a method for function 't' Cheers, Hank Dr. Hank Stevens, Assistant Professor 338 Pearson Hall Botany Department Miami University Oxford, OH 45056 Office: (513) 529-4206 Lab: (513) 529-4262 FAX: (513) 529-4243 http://www.cas.muohio.edu/~stevenmh/ http://www.muohio.edu/ecology/ http://www.muohio.edu/botany/ "E Pluribus Unum"
______________________________________________ R-help at 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.
Dr. Hank Stevens, Assistant Professor 338 Pearson Hall Botany Department Miami University Oxford, OH 45056 Office: (513) 529-4206 Lab: (513) 529-4262 FAX: (513) 529-4243 http://www.cas.muohio.edu/~stevenmh/ http://www.muohio.edu/ecology/ http://www.muohio.edu/botany/ "E Pluribus Unum"