Displaying 20 results from an estimated 20000 matches similar to: "Setting base level for contrasts with lme"
2006 Oct 09
1
split-plot analysis with lme()
Dear R-help,
Why can't lme cope with an incomplete whole plot when analysing a split-plot
experiment? For example:
R : Copyright 2006, The R Foundation for Statistical Computing
Version 2.3.1 (2006-06-01)
> library(nlme)
> attach(Oats)
> nitro <- ordered(nitro)
> fit <- lme(yield ~ Variety*nitro, random=~1|Block/Variety)
> anova(fit)
numDF denDF F-value
2010 Mar 18
2
Please Post Planned Contrasts Example in lme {nlme}
Hi I am running some linear and non-linear mixed effect models and would like to do some planned contrasts (a priori contrasts)
I have looked in the help and in many forums and it seems possible to do so but don't understand how to write the function and I couldn't find an example in Pinheiro and Bates.
lme {nlme} has a contrasts argument but I can't understand how to code it.
2008 Feb 03
3
Drawing a loess line
Dear all,
To draw a lowess line on a plot was a piece of cake; to draw a loess
line, however, seems not that easy. Is the loess plotting implemented
at all in relation to the loess function, or do I have to look in
add-on packages?
Thanks,
Marcin
2007 Apr 30
2
Independent contrasts from lme with interactions
Hi All,
I've been searching the help archives but haven't found a workable
solution to this problem.
I'm running an lme model with the following call:
>lme.fnl <- lme(Max ~ S + Tr + Yr + Tr:Yr, random = ~1 |TID)
> anova(lme.fnl)
numDF denDF F-value p-value
(Intercept) 1 168 19255.389 <.0001
S 1 168 5.912 0.0161
Tr
2007 Dec 06
3
Vertical text in a plot
Hi,
Consider this simple plot:
> plot(1:25,runif(25,0,1),ylab="First Y-axis label",xaxt="n")
I want to add an additional axis as
> axis(4,at=seq(0.2,1,.2), labels=1:5)
I have no idea how to add now the title of the new axis as "Second
Y-axis label". I want this text to be vertically directed from bottom
to top. I can't find the function in text() to write
2005 Feb 15
1
Correct effect plots from lme() objects
Hello all!
R2.0.1, W2k
I posted this question to the list last Sunday without getting any
replies on the list. I got two off the list though, suggesting me to
plot "manually" as a second step, from estimable() or intervals()
objects respectively. As this was not really what I wished for, I take
the risk to upset somebody with a trivial question, and re-post it (just
a little
2010 Jan 06
0
is aov equivalent to lme for split-plot analysis?
Dear R community,
I am trying to do a split-plot analysis as follows. I have a data set
(?morf?) with plant data from 6 ?blocks? at different latitudes, each
divided in 3 plots. The full-plot ?treatment? is ?soil type? and has
three levels. Within each plot I have two levels of radiation, coded as
?SUN? and ?SHADE?. I have data for several response traits for 30 plants
within each subplot,
2010 Jan 09
0
aov vs lme for split plot analysis
Dear R community,
I am trying to do a split-plot analysis as follows. I have a data set
(?morf?) with plant data from 6 ?blocks? at different latitudes, each
divided in 3 plots. The full-plot ?treatment? is ?soil type? and has
three levels. Within each plot I have two levels of radiation, coded as
?SUN? and ?SHADE?. I have data for several response traits for 30 plants
within each subplot,
2008 Feb 15
2
Controling width of boxes in boxplots
Hi,
I want to add boxplots to a scatterplot:
plot(x,y, xlim=c(80,120),ylim=c(80,120))
boxplot(y,add=TRUE,at=118)
boxplot(x,add=TRUE,at=118,horizontal=TRUE)
How can I control the width of the boxes (say, I'd like them to be of
width 3 in the variables' scales). I've tried the "width" parameter
but failed.
Thanks in advance,
Marcin
2007 Jul 09
1
similar limma's contrasts.fit() for lme (mixed effect model) object
Dear R help,
In limma package, contrasts.fit() function is very useful. I am
wondering whether there is a similar function for lme object, which
means given a mixed linear model fit, compute estimated coefficients
and standard errors for a given set of contrasts.
Thanks,
Shirley
2003 Oct 06
0
Log transformed values and contrasts in LME
Dear All
This is probably a very basic question for this list but I just wanted to
make sure that I am doing things right:
I have an LME model with 4 categorical variables and 2 continuous variables
(analysis of covariance model). I had to use a log transformation on the
data to achieve normality (log(x)-.1) and then I used contrast treatment to
compare differences between a baseline level
2001 Jun 15
1
contrasts in lm and lme
I am using RW 1.2.3. on an IBM PC 300GL.
Using the data bp.dat which accompanies
Helen Brown and Robin Prescott
1999 Applied Mixed Models in Medicine. Statistics in Practice.
John Wiley & Sons, Inc., New York, NY, USA
which is also found at www.med.ed.ac.uk/phs/mixed. The data file was opened
and initialized with
> dat <- read.table("bp.dat")
>
2003 Feb 10
1
Factor level comparisons in lme
Hello,
I''m trying to fit a linear mixed effects model of the form:
lme(y ~ x * Sex * Year, random=x|subject)
where Sex and Year are factors with two and three levels respectively. I
want to compare the fixed effects for each level to the overall mean, but
the default in R is to compare to the first level. This can be changed by
adding the term -1 to the righthand side of the model
2011 Nov 17
1
lme contrast Error in `$<-.data.frame`(`*tmp*`, "df", value = numeric(0)) :
I am trying to run a lme model and some contrast for a matrix .
lnY
[1] 10.911628 11.198557 11.316971 11.464869 11.575233 11.612101 11.755903
11.722035 11.757705 11.863744 11.846515 11.852721 11.866936 11.838452
11.946680 11.885509
[17] 11.583309 11.750082 11.756005 11.630797 11.705536 11.566722 11.679448
11.703521 NA 11.570949 11.716919 11.573343 11.733770 11.720801
11.804124 11.775074
2006 Sep 23
1
variance-covariance structure of random effects in lme
Dear R users,
I have a question about the patterned variance-covariance structure for the random effects in linear mixed effect model.
I am reading section 4.2.2 of "Mixed-Effects Models in S and S-Plus" by Jose Pinheiro and Douglas Bates.
There is an example of defining a compound symmetry variance-covariance structure for the random effects in a
split-plot experiment on varieties of
2009 Jan 17
1
Dendrogram with the UPGMA method
Hi,
I am clustering objects using the agnes() function and the UPGMA
clustering method (function = "average"). Everything works well, but
apparently something is wrong with the dendrogram. For example:
x<-c(102,102.1,112.5,113,100.3,108.2,101.1,104,105.5,106.3)
y<-c(110,111,110.2,112.1,119.5,122.1,102,112,112.5,115)
xy<-cbind(x,y)
library(cluster)
UPGMA.orig<-agnes(x)
2011 Jun 02
0
allowing individual level correlations to differ by cluster in lme in R
Dear R-listers,
I am fitting bivariate mixed models for cost-effectiveness data of cluster randomized trials using lme in R. So I have individuals nested within clusters. My response variable is a vector with bivariate response (individual level costs and effects) stacked into a single column. The covariates in my models are a constant and a treatment term. They are response-specific, e.g. a
2007 Mar 06
0
different random effects for each level of a factor in lme
I have an interesting lme - problem. The data is part of the Master
Thesis of my friend, and she had some problems analysing this data,
until one of her Jurors proposed to use linear mixed-effect models. I'm
trying to help her since she has no experience with R. I'm very used to
R but have very few experience with lme.
The group calls of one species of parrot were recorded at many
2006 Nov 22
1
differences between aov and lme
Hi,
we have a split-plot experiment in which we measured the yield of crop
fields. The factors we studied were:
B : 3 blocks
I : 2 main plots for presence of Irrigation
V : 2 plots for Varieties
N : 3 levels of Nitrogen
Each block contains two plots (irrigated or not) . Each plot is divided
into two secondary parcels for the two varieties.
Each of these parcels is divided into three subplots
2005 Oct 07
1
The mathematics inside lme()
Hello all!
Consider a dataset with a grouping structure, Group (factor)
Several treatments, Treat (factor)
Some sort of yield, Yield (numeric)
Something, possibly important, measured for each group; GroupCov (numeric)
To look for fixed effects from Treat on Yield, a first attempt could be:
m1 <- lm(Yield ~ Treat)
which gives, in a symmetric situation, the same estimated fixed effects as: