Displaying 11 results from an estimated 11 matches similar to: "Extracting correlation in a nlme model"
2008 Jul 18
3
How to cut data elements included in a text line
Hello,
assume I have an "unstructured" text line from a connection. Unfortunately,
it is in string format:
R> x
[1] "\talpha0\t-0.638\t0.4043\t0.4043\t-2.215\t-0.5765\t-0.137\t501\t2000"
How can I extract the data included in this string object "x" in order to
get the elements for the parameter vector called "alpha0", i.e.
-0.638 0.4043 0.0467
2006 Jun 05
1
Extracting Variance components
I can ask my question using and example from Chapter 1 of Pinheiro & Bates.
> # 1.4 An Analysis of Covariance Model
>
> OrthoFem <- Orthodont[ Orthodont$Sex == "Female", ]
> fm1OrthF <-
+ lme( distance ~ age, data = OrthoFem, random = ~ 1 | Subject )
> summary( fm1OrthF )
Linear mixed-effects model fit by REML
Data: OrthoFem
AIC BIC
2005 Sep 14
1
Random effect model
Dear R-help group,
I would like to model directly following random effect model:
Y_ik = M_ik + E_ik where M_ik ~ N(Mew_k,tau_k^2)
E_ik ~ N(0,s_ik^2)
i = number of study
k = number of treatment
---------------------------------------------------------------------------
I have practiced using the command from 'Mixed -Effects models in S and
S-plus'
2008 Nov 14
1
aov help
Please pardon an extremely naive question. I see related earlier
posts, but no responses which answer my particular question. In
general, I'm very confused about how to do variance decomposition with
random and mixed effects. Pointers to good tutorials or texts would
be greatly appreciated.
To give a specific example, page 193 of V&R, 3d Edition, illustrates
using raov assuming pure
2003 Mar 30
1
simple test of lme, questions on DF corrections
I''m a physicist working on fusion energy and dabble in statistics
only occasionally, so please excuse gaps in my statistical
knowledge. I''d appreciate any help that a real statistics expert
could provide. Most people in my field do only very simple
statistics, and I am trying to extend some work on multivariate
linear regression to account for significant between-group
2005 Aug 04
1
exact goodness-of-fit test
Hello,
I have a question concerning the R-function chisq.test.
For example, I have some count data which can be categorized as follows
class1: 15 observations
class2: 0 observations
class3: 3 observations
class4: 4 observations
I would like to test the hypothesis whether the population probabilities are all equal (=> Test for discrete uniform distribution)
If you have a small sample size
2012 Feb 02
0
glmer question
I would like to fit the following model:
logit(p_{ij}) = \mu + a_i + b_j
where a_i ~ N(0, \sigma_a^2) , b_j ~ N(0, \sigma_b^2) and \sigma_a
= \sigma_b.
Is it possible to fit a model with such a constraint on the variance
components in glmer?
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2004 Apr 05
3
2 lme questions
Greetings,
1) Is there a nice way of extracting the variance estimates from an lme fit? They don't seem to be part of the lme object.
2) In a series of simulations, I am finding that with ML fitting one of my random effect variances is sometimes being estimated as essentially zero with massive CI instead of the finite value it should have, whilst using REML I get the expected value. I guess
2009 Feb 28
0
Implementation of quasi-bayesian maximum likelihood estimation for normal mixtures
Hi,
as you can see in the topic, I am trying to fit a normal mixture
distribution with the approach suggested by Hamilton (1991). Since I
couldn't find any existing packages including the quasi-bayesian mle, I
have to write my own function. Unfortunately, I have absolutely no
experience in doing this.
If you're not familiar with the QB-MLE, I attached the formula as pdf.
The idea
2008 Aug 29
3
extract variance components
HI,
I would like to extract the variance components estimation in lme function
like
a.fit<-lme(distance~age, data=aaa, random=~day/subject)
There should be three variances \sigma_day, \sigma_{day %in% subject } and
\sigma_e.
I can extract the \sigma_e using something like a.fit$var. However, I cannot
manage to extract the first two variance components. I can only see the
results in
2008 Jan 31
0
How to calculate Intraclass-coefficient in 2-level Linear Mixed-Effects models?
Dear R-users,
consider a 2-level linear mixed effects model (LME) with random intercept
AND random slope for level 1 AND 2. Does anybody know how to calculate
Intraclass-coefficient (ICC) for highest (innermost) level 2 ??? In the
literature, I did not find an example for these kind of komplex models.
For 1-level Random-Intercept models it would be easy:
ICC = variance due to the clustering