Displaying 20 results from an estimated 3000 matches similar to: "Adjusting confidence intervals for paired t-tests of multiple endpoints"
2008 Sep 09
6
plotting group means
Hi all,
I want to plot the grouped means of some variables. The dependent variables
and the grouping factor are stored in different columns. I want to draw a
simple line-plot of means, in which the x-axis represents the variables and
y-axis represents the means. The means of the groups should be connected by
lines. So far, the only function that I could find comes closest to what I'm
2009 Jan 20
1
generalizing expand.table: table -> data.frame
In
http://tolstoy.newcastle.edu.au/R/e2/help/06/10/3064.html
a method was given for converting a frequency table to an expanded data
frame representing each
observation as a set of factors. A slightly modified version was later
included in the NCStats package,
only on http://rforge.net/ (and it has too many dependencies to be useful).
I've tried to make it more general, allowing an input
2008 Sep 08
2
How to preserve date format while aggregating
Hi
I have a dataframe in which some subjects appear in more than one row. I
want to extract the subject-rows which have the minimum date per subject. I
tried the following aggregate function.
attach(dataframe.xy)
aggregate(Date,list(SubjectID),min)
Unfortunately, the format of the Date-column changes to numeric, when I'm
applying this function. How can I preserve the date format?
Thanks
2008 Dec 19
1
diagonal lines in legends of ggplot2
Hi, I have the following problem with ggplot2: When I specify black contours
for bars in a barplot, ggplot automatically shows diagonal lines in the
legend boxes. Is there a way, to remove these diagonal lines?
Here's a simple example:
library(ggplot2)
df<-data.frame(x=gl(6,1),y=rnorm(6,100,50))
ggplot(df,aes(y=y,x=x,fill=x))+geom_bar(aes(group=x),colour='black',size=1)+
2008 Sep 19
1
getting line breaks with xtable
Sorry, for asking the same question again, but I got no reactions the last
time. Maybe it was just overseen by the experts.
I'm using the xtable function with Sweave and Lyx and I would like to know
how to get automatic line breaks for long strings in a column of the table.
I've learned from the Lyx wiki that the Latex command \linebreak produces
table cells with multiple lines. I tried to
2010 Sep 23
1
How to pass a model formula as argument to with.mids
Hello
I would like to pass a model formula as an argument to the with.mids
function from the mice package. The with.mids functon fits models to
multiply imputed data sets.
Here's a simple example
library(mice)
#Create multiple imputations on the nhanes data contained in the mice
package.
imp <- mice(nahnes)
#Fitting a linear model with each imputed data set the regular way works
2010 Jul 22
1
gam() and contrast
Dear All,
I met problems when doing contrast and now really need some help in the
model below:
Fit=gam(y~treat+SEQUENCE+PERIOD+SEX+s(x),data=dat,
random=list(SUBJID=~1),correlation=corAR1(form=~1|SUBJID))
And error message keeps coming out when I want to compare the differences
between treatments:
Diff=contrast(Fit,
list(treat=treatment[-placebo.pos]),list(treat="Placebo"),
2007 May 14
1
Nicely formatted summary table with mean, standard deviation or number and proportion
Dear all,
The incredibly useful Hmisc package provides a method to generate
summary tables that can be typeset in latex. The Alzola and Harrell book
"An introduction to S and the Hmisc and Design libraries" provides an
example that generates mean and quartiles for continuous variables, and
numbers and percentages for count variables: summary() with method =
'reverse'.
I
2007 May 17
2
How to analyse simple study: Placebo-controlled (2 groups) repeated measurements (ANOVA, ANCOA???)
Hallo!
I have two groups (placebo/verum), every subject is measured at 5 times, the first time t0 is the baseline measurement, t1 to t4 are the measurements after applying the medication (placebo or verum). The question is, if there is a significant difference in the two groups and how large the differnce is (95% confidence intervals).
Let me give sample data
# Data
2008 Mar 14
2
problems creating data frames
I am having two problems creating data frames that I have solutions, but
they really seem like kludges and I assume I just don't understand the
proper R way of doing things.
The first situation is I have an set of uneven data vectors. When I try to
use them to create a data frame I would like the bottoms of them padded with
NAs, without explicitly specifying that. When I do:
anxiety.data =
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
2007 Sep 27
1
windows device transparency issue
I read in a thread in r-help today that the windows device in 2.6 supports
transparency, so I tried an example and had some issues. The density plots
should be filled with transparent color in the following example (similar to
the points), however the color is "fully" transparent. This works in the
Cairo device, but not in the windows device.
Thanks,
--Matt
Matt Austin
2008 Jul 02
1
auto.key in xyplot in conjunction with panel.text
All,
I can't seem to get auto.key to work properly in an xyplot that is employing
panel.text. Specifically, I often change the default grouping colors then
use auto.key accordingly, but for some reason the same functionality isn't
working for this different type of plot. Any help much appreciated.
Cheers,
David
library("lattice")
dat = data.frame( Y = c(rnorm(18,1),
2013 Sep 13
1
Creating dummy vars with contrasts - why does the returned identity matrix contain all levels (and not n-1 levels) ?
Hello,
I have a problem with creating an identity matrix for glmnet by using the
contrasts function.
I have a factor with 4 levels.
When I create dummy variables I think there should be n-1 variables (in this
case 3) - so that the contrasts would be against the baseline level.
This is also what is written in the help file for 'contrasts'.
The problem is that the function
2002 May 27
1
nlme cross-over and fixed nested
I have problem getting the concept of a nested fixed variable into the nlme
scheme. I fear the question is very stupid. In the past I had asked this
before, and never got a reply (in other cases, the response was within
hours). I also checked the S-list, where several similar enquiries of other
people are orphaned.
We have a cross-over design, where patient are treated two weeks with
placebo,
2012 Oct 23
5
List of multidimensional arrays
Dear all,
I am trying to create a list, where each list element is a vector of
different length arrays that contain 2by2 matrices. To be more specific
there are 11 treatments that are compared with placebo (we have 11
comparisons) and each comparison is studied by a different number of trials
and each trial has a different number of missing participants in both arms.
The length of the list is
2003 Apr 11
1
Pearson's Chi-squared Test
How i can perform a Pearson's Chi-squared Test in this data set:
| Outcome
-----------------+-----------+----------------------------------+
Treatment | Sex | None |Some | Marked | Total
-----------------+------------+--------+--------+-------------+
Active | Female | 6 | 5 | 16 | 27
2009 Feb 02
2
parsing problem
Hi all,
I am trying to parse a vector for caliculating minimum in that vector the
vector having values like
1 Kontrolle
2 Placebo
3 125mg/kg
4 250mg/kg
5 500mg/kg
6 1000mg/kg
hear i tries for comverting it into numeric with using "as.numaric()"
function
but i got values like
5
6
2
3
4
1
it gives 1000mg/kg is the least one
but i have
2006 Sep 26
2
treatment effect at specific time point within mixed effects model
All,
The code below is for a pseudo dataset of repeated measures on patients
where there is also a treatment factor called "drug". Time is treated
as categorical.
What code is necessary to test for a treatment effect at a single time
point,
e.g., time = 3? Does the answer matter if the design is a crossover
design,
i.e, each patient received drug and placebo?
Finally, what would
2011 Mar 27
2
Hmisc summary.formula formats for binary and continuous variables
Hello,
I am using Hmisc summary.formula, latex and Sweave to produce tables for publication. Is it possible to change the formats for binary and continuous variables? I would prefer to show 35 (10%) and 1.5 (1.2-1.8) rather than 10% (35) and 1.2 / 1.5 / 1.8. Here is a simple example:
sex <- factor(sample(c("m","f"), 500, rep=TRUE))
age <- rnorm(500, 50, 5)
treatment