[R-sig-eco] Answers to "Fixing heteroscedasticity in mixed-effects model?"

2012-03-29 Thread Malin Pinsky
Hi all, Just to summarize the very helpful set of answers I got to my query (see below for the problem description). 1) Specify a variance structure to account for heterogeneity of residuals across different values of the explanatory variables (e.g., weights = varPower() in the lme() function the

Re: [R-sig-eco] Fixing heteroscedasticity in mixed-effects model?

2012-03-29 Thread Ben Bolker
Malin Pinsky writes: > I'm having problems fitting a mixed-effects model for an ecological > meta-analysis, and I'm curious if anyone has advice. In particular, > it's pretty clear that the variance in the residuals increases with > the predicted mean, but my normal fixes don't seem to be working

[R-sig-eco] R and WinBUGS

2012-03-29 Thread David Valentim Dias
Algorithms for bayesian inference (MCMC) cannot run fast enough inside a scripting language like R. Most authors create plugins to call their fast binary (C/C++) implementations inside of R. Just use them. I recommend JAGS and rjags. Better errors messages and good support from Plummer. Cya 2012/

[R-sig-eco] R and WinBUGS

2012-03-29 Thread Manuel Spínola
Dear list members, This is not a very specific question on R for ecological analysis, but is related. I have been in courses where R and WinBugs are used together for data analysis, however, I still don´t understand why R need to use WinBUGS to perform some bayesian analysis. I teach statistics