Displaying 20 results from an estimated 1000 matches similar to: "dunnett test questions"
2013 Feb 26
1
Getting the correct factor level as Dunnett control in glht()
Hello all,
I would like to do a Dunnett test in glht(). However, the factor level I
want to use as the control is not the first.
dunn1<-glht(model3, linfct = mcp(Container = "Dunnett"), alternative =
"less")
The factor container has 8 levels, so it would be nice not to manually
enter in all of the contrasts. I originally discovered glht() when
working with a glm model
2007 Feb 09
1
Help in using multcomp.
Hi All,
I am trying use 'multcomp' for multiple comparisons
after my ANOVA analysis. I have used the following
code to do ANOVA:
dat <- matrix(rnorm(45), nrow=5, ncol=9)
f <- gl(3,3,9, label=c("C", "Tl", "T2"))
aof <- function(x) {
m <- data.frame(f, x);
aov(x ~ f, m)
}
amod <- apply(dat,1,aof)
Now, how can I use
2007 Nov 21
1
multiple comparison (glht) problem
I am not sure whether there is a bug. When I tested the example given for "glht"
in the help, I entered the following error:
Running commands:
amod <- aov(minutes ~ blanket, data = recovery)
rht <- glht(amod, linfct = mcp(blanket = "Dunnett"),
alternative = "less")
Errors are:
Error in try(coef.(model)) : could not find function
2007 Nov 21
1
question about multiple comparison in ANOVA
I am not sure whether there is a bug. When I tested the example given
for "glht" in the help, I entered the following error:
Running commands:
amod <- aov(minutes ~ blanket, data = recovery)
rht <- glht(amod, linfct = mcp(blanket = "Dunnett"),
alternative = "less")
Errors are:
Error in try(coef.(model)) : could not find function
2008 Nov 18
1
Tukey HSD following lme
Hi everyone
I'm using Tukey HSD as post-hoc test following a lme analysis. I'm
measuring hemicelluloses in different species treated with three
different CO2 concentrations (l=low, m=medium, h=high). The whole
experiment is a split-plot design and the Tukey-function from the
package multcomp is suitable for lme-analysis with random factors.
The analysis works fine but I get a non
2007 Mar 30
2
ANOVA and confidence intervals plot
Dear *,
I would like to obtain for each factor of my anova model the
"response variable vs factor" plot with means and 95% Tukey HSD
intervals.
I would appreciate any information on how to do that.
Cheers
--------------------------------------------------------------------
Max MANFRIN Tel.: +32 (0)2 650 3168
IRIDIA - CoDE, CP 194/6
2011 Mar 04
2
glht: Problem with symbolic contrast for factors with number-levels
Using a factor with 'number' levels the straightforward
symbolic formulation of a contrast in 'glht' of
the 'multcomp' package fails.
How can this problem be resolved without having to redefine the factor levels?
Example:
#A is a factor with 'number' levels
#B similar factor with 'letter' levels
dat<-data.frame(y=1:4,A=factor(c(1,1,2,2)),
2011 Mar 01
1
Pairwise T-Tests and Dunnett's Test (possibly using multcomp)
Hello Everyone,
I've been learning to use R in my spare time over the past several months. I've read about 7-8 books on the subject. Lately I've been testing what I've learned by trying to replicate the analyses from some of my SAS books. This helps me make sure I know how to use R properly and also helps me to understand how the two programs are similar and different.
Below is
2009 Oct 19
1
Reposting various problems with two-way anova, lme, etc.
Hi,
I posted the message below last week, but no answers, so I'm giving it
another attempt in case somebody who would be able to help might have missed
it and it has now dropped off the end of the list of mails.
I am fairly new to R and still trying to figure out how it all works, and I
have run into a few issues. I apologize in advance if my questions are a bit
basic, I'm also no
2007 Mar 18
1
multcomp
I used the multcomp package sometime back for doing multiple
comparisons. I see that it has been updated and the methods like simint
are no longer supported. When I run the program it prompts to me to use
glht. How do I get the lower and upper conf int and the pValues using
glht? Does anyone have an example?
Thanks ../Murli
[[alternative HTML version deleted]]
2011 Mar 01
1
glht() used with coxph()
Hi, I am experimenting with using glht() from multcomp package together with
coxph(), and glad to find that glht() can work on coph object, for example:
> (fit<-coxph(Surv(stop, status>0)~treatment,bladder1))
coxph(formula = Surv(stop, status > 0) ~ treatment, data = bladder1)
coef exp(coef) se(coef) z p
treatmentpyridoxine -0.063 0.939 0.161
2010 May 17
1
Query on linear mixed model
Hi R Forum
I am a newbie to R and I have been amazed by what
I can get my team to accomplish just by
implementing Scripting routines of R in all my
team's areas of interest..
Recently i have been trying to adopt R scripting
routine for some analysis with longitudanal data..
I am presenting my R script below that I have
tried to make to automate data analysis for
longitudanal data by employing
2008 Nov 14
3
Change Confidence Limits on a plot
Hi,
I am attempting to set the confidence limits on a ls means plot as follows:
mult<-glht(lm(effectModel, data=statdata, na.action = na.omit),
linfct=mcp(mainEffect="Means"))
meanPlot <- sub(".html", "meanplot.jpg", htmlFile)
jpeg(meanPlot)
plot(mult, main=NA, xlab=unlist(strsplit(Args[4],"~"))[1])
This produces 95% CIs by default but I would
2013 Jul 25
1
lme (weights) and glht
Dear R members,
I tried to fit an lme model and to use the glht function of multcomp.
However, the glht function gives me some errors when using
weights=varPower().
The glht error makes sense as glht needs factor levels and the model
works fine without weights=. Does anyone know a solution so I do not
have to change the lme model?
Thanks
Sibylle
--> works fine
2012 Jan 02
1
Is using glht with "Tukey" for lme post-hoc comparisons an appropriate substitute to TukeyHSD?
Hello,
I am trying to determine the most appropriate way to run post-hoc
comparisons on my lme model. I had originally planned to use Tukey
HSD method as I am interested in all possible comparisons between my
treatment levels. TukeyHSD, however, does not work with lme. The
only other code that I was able to find, and which also seems to be
widely used, is glht specified with Tukey:
2011 Jul 26
3
a question about glht function
Hi all:
There's a question about glht function.
My data:data_ori,which inclue CD4, GROUP,time.
f_GROUP<-factor(data_ori$GROUP)
f_GROUP is a factor of 3 levels(0,1,2,3)
result <- lme(sqrt(CD4) ~ f_GROUP*time ,random = ~time|ID,data=data_ori)
glht(result, linfct = mcp(f_GROUP="Tukey") )
Error in `[.data.frame`(mf, nhypo[checknm]) : undefined columns selected
I can't
2009 Mar 22
1
Multiple Comparisons for (multicomp - glht) for glm negative binomial (glm.nb)
Hi
I have some experimental data where I have counts of the number of
insects collected to different trap types rotated through 5 different
location (variable -location), 4 different chemical attractants [A, B,
C, D] were applied to the traps (variable - semio) and all were
trialled at two different CO2 release rates [1, 2] (variable CO2) I also
have a selection of continuous variables
2009 Nov 05
1
Newbie question Multcomp
Hello, I'm a totally newbie to R and I'm taking a class using S+.
In the class we use the multcomp command which takes a aov object and
calculates confidence intervals for all pairwise differences by the Fisher
least significant differences method.
How can I do this in R.
Thank you for taking the time with such a basic question. I've been looking
on the net for a few days and I
2010 Jul 21
1
post hoc test for lme using glht ?
Hi,
I have a fairly simple repeated measures-type data set I've been attempting
to analyze using the lme function in the nlme package. Repeated searches
here and other places lead me to believe I have specified my model
correctly.
However, I am having trouble with post-hoc tests. From what I gather, other
people are successfully using the glht function from the multcomp package to
2011 Aug 06
1
multcomp::glht() doesn't work for an incomplete factorial using aov()?
Hi R users,
I sent a message yesterday about NA in model estimates (
http://r.789695.n4.nabble.com/How-set-lm-to-don-t-return-NA-in-summary-td3722587.html).
If I use aov() instead of lm() I get no NA in model estimates and I use
gmodels::estimable() without problems. Ok!
Now I'm performing a lot of contrasts and I need correcting for
multiplicity. So, I can use multcomp::glht() for this.