Displaying 20 results from an estimated 2000 matches similar to: "mcmcsamp - How does it work?"
2006 Sep 28
2
get index of elements in vector
Hello all
Is There a fuction that return a index of a element in vector?
like this semantic example:
vector = c( 100, 200, 300 )
getINDEX( vector, value = 200 )
Thanks in advance for your attention.
Cleber Borges
2006 Aug 08
1
fixed effects constant in mcmcsamp
I'm fitting a GLMM to some questionnaire data. The structure is J individuals,
nested within I areas, all of whom answer the same K (ordinal) questions. The
model I'm using is based on so-called continuation ratios, so that it can be
fitted using the lme4 package.
The lmer function fits the model just fine, but using mcmcsamp to judge the
variability of the parameter estimates produces
2006 Aug 08
1
fixed effects following lmer and mcmcsamp - which to present?
Dear all,
I am running a mixed model using lmer. In order to obtain CI of
individual coefficients I use mcmcsamp. However, I need advice which
values that are most appropriate to present in result section of a
paper. I have not used mixed models and lmer so much before so my
question is probably very naive. However, to avoid to much problems with
journal editors and referees addicted to
2009 Feb 11
2
generalized mixed model + mcmcsamp
Hi,
I have fitted a generalized linear mixed effects model using lmer
(library lme4), and the family = quasibinomial. I have tried to obtain a
MCMC sample, but on calling mcmcsamp(model1, 1000) I get the following
error which I don't understand at all:
Error in .local(object, n, verbose, ...) : Update not yet written
traceback() delivers:
4: .Call(mer_MCMCsamp, ans, object)
3:
2006 Oct 16
2
New package Ryacas
Ryacas is an R interface to the free yacas computer algebra
system. Ryacas allows one to send R expressions,
unprocessed yacas strings and certain other R objects to a
separate yacas process from R and get back the result. It
also has facilities for manipulating yacas strings and R
expressions destined for yacas processing.
It can be used for exact arithmetic, symbolic math, ASCII
pretty
2006 Oct 16
2
New package Ryacas
Ryacas is an R interface to the free yacas computer algebra
system. Ryacas allows one to send R expressions,
unprocessed yacas strings and certain other R objects to a
separate yacas process from R and get back the result. It
also has facilities for manipulating yacas strings and R
expressions destined for yacas processing.
It can be used for exact arithmetic, symbolic math, ASCII
pretty
2006 Oct 16
2
New package Ryacas
Ryacas is an R interface to the free yacas computer algebra
system. Ryacas allows one to send R expressions,
unprocessed yacas strings and certain other R objects to a
separate yacas process from R and get back the result. It
also has facilities for manipulating yacas strings and R
expressions destined for yacas processing.
It can be used for exact arithmetic, symbolic math, ASCII
pretty
2007 Aug 21
1
small issue with densityplot
Hi folks,
This is really minor but to someone not familiar with the various tentacles of the lmer package it could be really annoying. I was trying to plot the posterior density of the fixed effect parameters of a lmer model,
> hr.mcmc = mcmcsamp(hr.lmer, n=50000)
> densityplot(hr.mcmc, plot.points=F)
There is this error,
"Error in densityplot(hr.mcmc, plot.points = F) :
no
2006 Feb 10
1
mcmcsamp shortening variable names; how can i turn this feature off?
I have written a function called mcsamp() that is a wrapper that runs
mcmcsamp() and automatically monitors convergence and structures the
inferences into vectors and arrays as appropriate.
But I have run into a very little problem, which is that mcmcsamp()
shortens the variable names. For example:
> set.seed (1)
> group <- rep (1:5,10)
> a <- rnorm (5,-3,3)
> y <-
2013 May 08
1
How to calculate Hightest Posterior Density (HPD) of coeficients in a simple regression (lm) in R?
Hi!
I am trying to calculate HPD for the coeficients of regression models
fitted with lm or lmrob in R, pretty much in the same way that can be
accomplished by the association of mcmcsamp and HPDinterval functions for
multilevel models fitted with lmer. Can anyone point me in the right
direction on which packages/how to implement this?
Thanks for your time!
R.
[[alternative HTML version
2010 Jan 31
2
lmer, mcmcsamp, coda, HPDinterval
Hi,
I've got a linear mixed model created using lmer:
A6mlm <- lmer(Score ~ division + (1|school), data=Age6m)
(To those of you to whom this model looks familiar, thanks for your patience
with this & my other questions.) Anyway, I was trying this to look at the
significance of my fixed effects:
A6post <- mcmcsamp(A6mlm, 50000)
library(coda)
HPDinterval(A6post)
..but I got this
2008 Oct 08
1
Suspicious output from lme4-mcmcsamp
Hello, R community,
I have been using the lmer and mcmcsamp functions in R with some difficulty. I do not believe this is my code or data, however, because my attempts to use the sample code and 'sleepstudy' data provided with the lme4 packaged (and used on several R-Wiki pages) do not return the same results as those indicated in the help pages. For instance:
> sessionInfo()
R
2007 Apr 27
1
Example of mcmcsamp() failing with lmer() output
Hi,
I would appreciate help with the following model
<<1>>=
gunload <- read.table(hh('datasets/gunload.dat'), header = T)
gunload$method <- factor(gunload$method, labels = c('new', 'old'))
gunload$physique <- factor(gunload$group, labels = c('slight',
'average', 'heavy'))
gunload$team9 <- factor(rep(1:9, each = 2))
@
This
2008 Sep 27
1
Using the mcmcsamp function
Hello,
I'm building a couple of mixed models using the lmer function.
The actual modelling is going well, but doing some reading on the use of
crossed random effects and the comparison of models with and without
random effects it is clear that I need to generate some Markov Chain Monte
Carlo samples. However, I'm struggling because everyone time I go to
generate a sample I get the
2007 Jan 03
1
mcmcsamp and variance ratios
Hi folks,
I have assumed that ratios of variance components (Fst and Qst in
population genetics) could be estimated using the output of mcmcsamp
(the series on mcmc sample estimates of variance components).
What I have started to do is to use the matrix output that included
the log(variances), exponentiate, calculate the relevant ratio, and
apply either quantile or or HPDinterval to get
2009 Feb 24
2
lmer, estimation of p-values and mcmcsamp
(To the list moderator: I just subscribed to the list. Apologies for not
having done so longer before trying to post.)
Hi all,
I am currently using lmer to analyze data from an experiment with a
single fixed factor (treatment, 6 levels) and a single random factor
(block). I've been trying to follow the online guidance for estimating
p-values for parameter estimates on these and other
2006 Nov 29
1
Lmer, P-values and mixed logistic regression
Hi
I know that p-values doesn't appear anymore in the summary of a linear
mixed-model with lmer. However, if I do a mixed logistic regression with
lmer using family=binomial, the summary includes a p-values for fixed
effects.
Is it normal, could I use those p-values to interpret the fixed effects
or should I use mcmcsamp to obtain 95% confidence interval?
Thanks
Julien
2007 Mar 30
0
problem using mcmcsamp() with glmer models containing interaction terms in fixed effects
Dear All,
I've been using mcmcsamp() successfully with a few different mixed models
but I can't get it to work with the following. Is there an obvious reason
why it shouldn't work with a model of this structure ?
*brief summary of objective:
I want to test the effect of no-fishing marine reserves on the abundance of
a target species.
I have samples at coral reef sites inside and
2008 Jan 24
0
(lme4: lmer) mcmcsamp: Error in if (var(y) == 0)
I've got a problem with "mcmcsamp" used with glmer objects produced
with "lmer" from the lme4 package.
When calling mcmcsamp, I get the error
Error in if (var(y) == 0) { : missing value where TRUE/FALSE needed
This does not occur with all models, but I can't find anything wrong
with the dataset.
If the error is in my data, can someone tell me what I am looking
2011 Feb 19
0
lmer, MCMCsamp and ranef samples?
I really hope sombody could help me with the following,
I'm having problems accessing the random effect samples following the
example on MCMCsamp:
(fm1 <- lmer(Reaction ~ Days + (1|Subject) + (0+Days|Subject), sleepstudy))
set.seed(101); samp0 <- mcmcsamp(fm1, n = 1000, saveb=TRUE)
str(samp0)
Formal class 'merMCMC' [package "lme4"] with 9 slots
..@ Gp :