Displaying 20 results from an estimated 5000 matches similar to: "odds ratio: how to create reference"
2008 Sep 29
2
density estimate
Hi,
I have a vector or random variables and I'm estimating the density using
"bkde" function in the KernSmooth package. The out put contains two vectors
(x and y), and the R documentation calls y as the density estimates, but my
y-values are not exact density etstimates (since these are numbers larger
than 1)! what is y here? Is it possible to get the true estimated density at
each
2008 Sep 22
2
Coefficients, OR and 95% CL
Dear R-users,
After running a logistic regression, I need to calculate OR by exponentiating the coefficient, and then I need the 95% CL for the OR as well. For the following example (taken from P. Dalaagard's book), what would be the most straightforward method of getting what I need? Could anyone enlight me please?
Thank you!
Lucho
> summary(glm(menarche~age,binomial))
Call:
2007 Nov 15
2
font formating
I am tryindo to do a very simple thing but cannont find how to do it
anywhere. I need to formap part of my title as subscript ans superscript.
How can I do it?
Thanks a lot in advance
José
--
MSc José Alberto F. Monteiro
Botanisches Institut
Universität Basel
[[alternative HTML version deleted]]
2009 Feb 19
2
read.table : how to condition on error while opening file?
Hi,
I'm using read.table in a loop, to read in multiple files. The problem
is that when a file is missing there is an error message and the loop is
broken; what I'd like to do is to test for the error and simply do
"next" instead of breaking the loop. Anybody knows how to do that?
Example:
filelist <- c("file1.txt", "file2.txt",
2009 Apr 07
4
group by-like statement for 2-row matrix
Hi,
my problem is as follows:
I have a matrix of two rows like this:
2 2 3 4 4 4 5 5 6
1 1 2 1 3 3 2 1 1
Can I apply something like "group by" in sql? What I want to achieve
is the some of second row for each unique entry of first row:
2 -> 2 (=1+1)
3 -> 2
4 -> 7 (=1+3+3)
5 -> 3 (=2+1)
6 -> 1
Thanks!!
Henning
2007 Oct 01
4
Disentagling formulas
I am writing a program in which I would like to take in a formula, change the response (Y) variable into something else, and then pass the formula, with the new Y variable to another function. That is, I am starting with
formula <- Y~X1+X2+X3
and I'd like to do something like
Y <- formula$Y
newY <- f(Y)
lm(newY~X1+X2+X3)
So far, it seems that my
2007 Mar 01
7
count the # of appearances...
Hi there,
is there a possibility to count the number of appearances of an
element in a vector ?
i mean of any given element.. deliver all elements which are exactly
xtimes in this vector ?
thx in advance !!
2008 Jul 12
5
shapiro wilk normality test
Hi everybody,
somehow i dont get the shapiro wilk test for normality. i just can?t
find what the H0 is .
i tried :
shapiro.test(rnorm(5000))
Shapiro-Wilk normality test
data: rnorm(5000)
W = 0.9997, p-value = 0.6205
If normality is the H0, the test says it?s probably not normal, doesn
?t it ?
5000 is the biggest n allowed by the test...
are there any other test ? ( i know qqnorm
2010 Apr 28
7
operator problem within function
Dear all,
i have a problem with processing dataframes within a function using the "$".
Here´s my code:
recode_items = function(dataframe,number,medium=2){
# this works
q<-paste("columna",number,sep="")
# this does not work, particularly because "dataframe" is not processed
# dataframe should be: givenframe$columnagivennumber
2007 Feb 27
5
Multiple conditional without if
Dear all,
i am stuck with a syntax problem.
i have a matrix which has about 500 rows and 6 columns.
now i want to kick some data out.
i want create a new matrix which is basically the old one except for all
entries which have a 4 in the 5 column AND a 1 in the 6th column.
i tried the following but couldn´t get a new matrix, just some wierd
errors:
2008 Jan 06
3
run setwd at the launch of R
Dear all,
my R files (and the .csv files as well) are saved somewhere pretty
deep down my hard disk.
i have to chage to working directory therefore everytime i run R (i
run it on powerPC mac), which is disgusting.
using the setwd command at the beginning of an R script doesnt really
help because i have to find this file first by hand.
I am looking for possibility to run setwd during the
2009 Feb 17
3
Combination
Hello,
I have a sequence of numbers:
seq(1:50)
and I would like to have all the possible combinations with this numbers
without repeating any combination:
11, 12, 13, ... ,22,23,24,...
How can I do it?
Best,
Dani
--
Daniel Valverde Saub?
Grup de Biologia Molecular de Llevats
Facultat de Veterin?ria de la Universitat Aut?noma de Barcelona
Edifici V, Campus UAB
08193 Cerdanyola del Vall?s-
2009 Mar 24
4
multiple paired t-tests
Hi R users,
I have a very large data set that has two conditioning variables for the
test I want to perform.
A toy set can be simulated:
type<-sample(1:3,100,replace=TRUE)
class<-sample(1:20,100,replace=TRUE)
value<-rnorm(100)
data<-cbind(type,class,value)
(though type and class are alphanum)
I want to perform the three pair-wise t-tests between types for each
class in data.
Can
2007 Mar 07
5
hwo can i get a vector that...
dear all,
how can i get a vector that shows the number of the column of matrix
that contains the maximum of the row ??
can?t believe in need a loop for this...
i have a 100 x 3 matrix and want to get a 100 x 1 vector with values
1,2,3 .
there must be a simple solution. i just cannot find it. i think am
searching on the wrong end.
thx for help in advance.
m.
2010 Jun 01
3
lapply with functions with changing parameters
Dear all,
I am trying to avoid a for loop here and wonder if the following is possible:
I have a data.frame with 6 columns and i want to get a cross-correlogram (by using ccf) . Obivously ccf only accepts two columns at once and then returms a list.
In fact, with a for loop i?d do the following
for (i in 1:6) {
x[[i]]=ccf(mydf[,i],mydf[,6])
}
Is there any chance to the same with
2009 Apr 07
6
Sequences
Hi,
I am trying to make a sequence and am using a for loop for this. I want to
start off with an initial value ie S[0]=0 then use the loop to create other
values. This is what I have so far but I just keep getting error messages.
#To calculate the culmulative sums:
s<-rep(0,207) #as this is the length of the
vector I know I will have
s<-as.vector(s)
2008 Sep 17
3
t-test between percentages
Hi all,
though i know this is a simple question, i really hope someone could.
I am just trying to compare percents respectively the difference in
percents by a simple test. t.test usually compares means and is
working like it is supposed to be. Now i wonder how i can use a test
in R to test for significant difference between two percentages.
2009 Apr 08
2
Null-Hypothesis
Hello R users,
I've used the following help two compare two regression line slopes.
Wanted to test if they differ significantly:
Hi,
I've made a research about how to compare two regression line slopes
(of y versus x for 2 groups, "group" being a factor ) using R.
I knew the method based on the following statement :
t = (b1 - b2) / sb1,b2
where b1 and b2 are the two slope
2010 Feb 03
1
plm package index
Dear all,
i just wonder if there´s a way to use a two column time index field in plm package.
the manual says the following concerning data indexing:
a character vector of length two containing the names of the individual and the time
index,
What would y´all do with a quarterly dataset that contains one column for the period and one for the year. Do I have to convert it to one single date
2009 Jan 13
5
indexing question
Hi all,
i have a pretty easy indexing question, at least i believe so. The
main reason i post it here, is that brackets and $ are hard to google.
How do I index correctly, if i just want to display the whole dataset
conditioned on the fact that some particular column equals one.
I know i can do something like: data$somecolumn[data$particularcol
==1] . That will show all "some