Displaying 20 results from an estimated 2000 matches similar to: "simple test of lme, questions on DF corrections"
2003 Apr 18
1
Help with nlme--freq weights, logit model, and more
Below you will find the output from a failed multi-level model run. I am
trying to estimate the following model:
Pr(PLFP=1)= logistic regression ->
B1_j * bm + B2_j * wm + B3_j bf + B4_j wf + B5 yrsed+ B6 age+ B7 age^2+e_ij
B1_j = G01 + G11 bmxd + d1
B2_j = G02 + G12 wmxd + d2
B3_j = G03 + G13 bfxd + d3
B4_j = G04 + G14 wfxd + d4
d1-d4 freely correlated
Note that there is no
2004 Feb 06
0
Restrict logon to groups of workstations II
After sending my first email, I tried to modify auth/auth_sam.c to
allow groups of workstations to the workstations list. And, for my
surprise (?!) it was quite easy. And worked fine. I use LDAP as sam
backed, and for unix accounts and groups database. I create a test group
"stations" and putted there into two of my workstations. Then I defined
the "sambaUserWorkstations"
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'
2009 May 20
1
Extracting correlation in a nlme model
Hi R users:
Is there a function to obtain the correlation within groups
from this very simple lme model?
> modeloMx1
Linear mixed-effects model fit by REML
Data: barrag
Log-restricted-likelihood: -70.92739
Fixed: fza_tension ~ 1
(Intercept)
90.86667
Random effects:
Formula: ~1 | molde
(Intercept) Residual
StdDev: 2.610052 2.412176
Number of Observations: 30
Number
2005 Mar 28
1
mixed model question
I am trying to fit a linear mixed model of the form
y_ij = X_ij \beta + delta_i + e_ij
where e_ij ~N(0,s^2_ij) with s_ij known
and delta_i~N(0,tau^2)
I looked at the ecme routine in package:pan, but this routine
does not allow for different Vi (variance covariance matrix of
the e_i vector) matrices for each cluster.
Is there an easy way to fit this model in R or should I bite the
bullet and
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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2006 Mar 21
1
Scaling behavior ov bVar from lmer models
Hi all,
To follow up on an older thread, it was suggested that the following
would produce confidence intervals for the estimated BLUPs from a linear
mixed effect model:
OrthoFem<-Orthodont[Orthodont$Sex=="Female",]
fm1OrthF. <- lmer(distance~age+(age|Subject), data=OrthoFem)
fm1.s <- coef(fm1OrthF.)$Subject
fm1.s.var <- fm1OrthF. at bVar$Subject
fm1.s0.s <-
2007 Nov 09
1
Confidence Intervals for Random Effect BLUP's
I want to compute confidence intervals for the random effect estimates
for each subject. From checking on postings, this is what I cobbled
together using Orthodont data.frame as an example. There was some
discussion of how to properly access lmer slots and bVar, but I'm not
sure I understood. Is the approach shown below correct?
Rick B.
# Orthodont is from nlme (can't have both nlme and
2006 Jun 05
1
Extracting Variance components
I can ask my question using and example from Chapter 1 of Pinheiro & Bates.
> # 1.4 An Analysis of Covariance Model
>
> OrthoFem <- Orthodont[ Orthodont$Sex == "Female", ]
> fm1OrthF <-
+ lme( distance ~ age, data = OrthoFem, random = ~ 1 | Subject )
> summary( fm1OrthF )
Linear mixed-effects model fit by REML
Data: OrthoFem
AIC BIC
2006 Oct 18
1
lmer- why do AIC, BIC, loglik change?
Hi all,
I am having issues comparing models with lmer. As an example, when
I run the code below the model summaries (AIC, BIC, loglik) differ between
the summary() and anova() commands. Can anyone clear up what's wrong?
Thank you!
Darren Ward
library(lme4)
data(sleepstudy)
fm1<-lmer(Reaction ~ Days + (1|Subject), sleepstudy)
summary(fm1)
fm2<-lmer(Reaction ~ Days +
2009 Jan 28
1
gls prediction using the correlation structure in nlme
How does one coerce predict.gls to incorporate the fitted correlation
structure from the gls object into predictions? In the example below
the AR(1) process with phi=0.545 is not used with predict.gls. Is
there another function that does this? I'm going to want to fit a few
dozen models varying in order from AR(1) to AR(3) and would like to
look at the fits with the correlation structure
2012 Oct 23
1
How Rcmdr or na.exclude blocks TukeyHSD
Dear R-Helpers,
I was calling the TukeyHSD function and not getting confidence intervals or p-values. It turns out this was caused by missing data and the fact that I had previously turned on R Commander (Rcmdr). John Fox knew that Rcmdr sets na.action to na.exclude, which causes the problem. If you have this problem, you can either exit Rcmdr before calling TukeyHSD or you can set na.action to
2002 Dec 17
1
lme invocation
Hi Folks,
I'm trying to understand the model specification formalities
for 'lme', and the documentation is leaving me a bit confused.
Specifically, using the example dataset 'Orthodont' in the
'nlme' package, first I use the invocation given in the example
shown by "?lme":
> fm1 <- lme(distance ~ age, data = Orthodont) # random is ~ age
Despite the
2002 Nov 24
1
Understanding function residuals()
Hello:
I am trying to understand why glm() does not replicate the results in
Dobson, "Introduction to Generalized Linear Models," pp. 17-20.
I set up the following model. The variable CONDT is assumed as Poisson and
the objective is to estimate the expected value.
The data (chronic medical conditions among women in Australia) is as
follows:
CONDT <- c(0, 1, 1, 0, 2, 3, 0, 1,
2006 Mar 13
2
Error Message from Variogram.lme Example
When I try to run the example from Variogram with an lme object, I get
an error (although summary works):
R : Copyright 2005, The R Foundation for Statistical Computing
Version 2.2.1 (2005-12-20 r36812)
ISBN 3-900051-07-0
...
> fm1 <- lme(weight ~ Time * Diet, BodyWeight, ~ Time | Rat)
Error: couldn't find function "lme"
> Variogram(fm1, form = ~ Time | Rat, nint =
2006 Dec 10
0
lmer, gamma family, log link: interpreting random effects
Dear all,
I'm curious about how to interpret the results of the following code.
The first model is directly from the help page of lmer; the second is
the same model but using the Gamma family with log link. The fixed
effects make sense, because
y = 251.40510 + 10.46729 * Days
is about the same as
log(y) = 5.53613298 + 0.03502057 * Days
but the random effects seem quite
2005 Feb 02
0
Not reproducing GLS estimates
Dear List:
I am having some trouble reproducing some GLS estimates using matrix
operations that I am not having with other R procedures. Here are some
sample data to see what I am doing along with all code:
mu<-c(100,150,200,250)
Sigma<-matrix(c(400,80,16,3.2,80,400,80,16,16,80,400,80,3.2,16,80,400),n
c=4)
sample.size<-100
temp <-
2002 Dec 15
2
Interpretation of hypothesis tests for mixed models
My question concerns the logic behind hypothesis tests for fixed-effect
terms in models fitted with lme. Suppose the levels of Subj indicate a
grouping structure (k subjects) and Trt is a two-level factor (two
treatments) for which there are several (n) responses y from each
treatment and subject combination. If one suspects a subject by
treatment interaction, either of the following models seem
2005 Nov 17
1
anova.gls from nlme on multiple arguments within a function fails
Dear All --
I am trying to use within a little table producing code an anova
comparison of two gls fitted objects, contained in a list of such
object, obtained using nlme function gls.
The anova procedure fails to locate the second of the objects.
The following code, borrowed from the help page of anova.gls,
exemplifies:
--------------- start example code ---------------
library(nlme)
##
2012 Feb 09
1
Tukey HSD
Hey Folks:
New to R and learning as I go, but really, I know just enough to get myself
into trouble. I've waded through everything up till now, and don't see
anything in the search that is directly helpful for the POS that I've
created.
The GOAL: All I want in the world is a program that performs 1-way ANOVA's
on every column in a data set (taking the first column as the