Displaying 20 results from an estimated 7000 matches similar to: "t-test between percentages"
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
2008 Jun 30
3
Is there a good package for multiple imputation of missing values in R?
I'm looking for a package that has a start-of-the-art method of
imputation of missing values in a data frame with both continuous and
factor columns.
I've found transcan() in 'Hmisc', which appears to be possibly suited
to my needs, but I haven't been able to figure out how to get a new
data frame with the imputed values replaced (I don't have Herrell's book).
Any
2011 Jun 05
3
How to convert a factor column into a numeric one?
I have a data frame:
> head(df)
Time Temp Conc Repl Log10
1 0 -20 H 1 6.406547
2 2 -20 H 1 5.738683
3 7 -20 H 1 5.796394
4 14 -20 H 1 4.413691
5 0 4 H 1 6.406547
7 7 4 H 1 5.705433
> str(df)
'data.frame': 177 obs. of 5 variables:
$ Time : Factor w/ 4 levels
2007 May 03
4
Survival statistics--displaying multiple plots
Hello all!
I am once again analyzing patient survival data with chronic liver disease.
The severity of the liver disease is given by a number which is continuously
variable. I have referred to this number as "meld"--model for end stage
liver disease--which is the result of a mathematical calculation on
underlying laboratory values. So, for example, I can generate a Kaplan-Meier
plot
2008 Apr 22
2
Multidimensional contingency tables
How does one ideally handle and display multidimenstional contingency
tables in R v. 2.6.2?
E.g.:
> prob1<- data.frame(victim=c(rep('white',4),rep('black',4)),
+ perp=c(rep('white',2),rep('black',2),rep('white',2),rep('black',2)),
+ death=rep(c('yes','no'),4), count=c(19,132,11,52,0,9,6,97))
> prob1
victim perp
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 !!
2006 Nov 24
2
vector problem
Hello out there,
i am not yet that experienced and trying to my best on a real survey.
but i am stuck with a little matrix / vector problem.
my vector of answers could have a length of 3 or only one. i want to
rbind all the answers into one matrix. (one vector for each participant)
answers vectors for one participant could look like:
p1: 100
p2: 20 80
p3: 40 10 50
i have the following
2007 Sep 10
1
S-Plus "resample" package and associated functions
Are there any packages in R that reproduce the package "resample" of S-Plus?
The sample() function in R doesn't provide equivalent flexibility of
bootstrap() and bootstrap2().
================================================================
Robert A. LaBudde, PhD, PAS, Dpl. ACAFS e-mail: ral at lcfltd.com
Least Cost Formulations, Ltd. URL: http://lcfltd.com/
824
2008 Sep 25
1
R function which finds confidence interval for binomial variance
I need to construct confidence intervals for the binomial variance.
This is the usual estimate
v = x*(n-x)/n
or its unbiased counterpart
v' = x*(n-x)/(n-1)
where x = binomial number of successes observed in n Bernoulli trials
from proportion p.
The usual X^2 method for variance confidence intervals will not work,
because of the strong non-normal character of the sampling
2010 Jun 21
2
Singularity in simple ANCOVA problem
I'm using R 2.10.1 with the latest version of all packages (updated today).
I'm confused as to why I'm getting a hard singularity in a simple set
of experimental data:
> blots
ID Lot Age Conc
1 1 A 3 4.44
2 2 A 3 4.56
3 3 B 41 4.03
4 4 B 41 4.57
5 5 C 229 4.49
6 6 C 229 4.66
7 7 D 238 3.88
8 8 D 238 3.93
9 9 E 349 4.43
10 10 E 349
2011 Feb 09
2
comparing proportions
Hi, I have a dataset that has 2 groups of samples. For each sample, then
response measured is the number of success (no.success) obatined with the number
of trials (no.trials). So a porportion of success (prpop.success) can be
computed as no.success/no.trials. Now the objective is to test if there is a
statistical significant difference in the proportion of success between the 2
groups of
2009 Sep 03
1
Problem accessing functions in package 'roxygen'
I have Vista Home with R-2.9.0, and installed and tried to test the
package 'roxygen':
> utils:::menuInstallPkgs()
trying URL
'http://lib.stat.cmu.edu/R/CRAN/bin/windows/contrib/2.9/roxygen_0.1.zip'
Content type 'application/zip' length 699474 bytes (683 Kb)
opened URL
downloaded 683 Kb
package 'roxygen' successfully unpacked and MD5 sums checked
The
2008 Apr 10
1
Problem installing and using package "tseries"
I have R 2.6.2, and have tried downloading and installing the package
"tseries". I get the same error when I use two different mirror sites:
> utils:::menuInstallPkgs()
trying URL
'http://cran.mirrors.hoobly.com/bin/windows/contrib/2.6/tseries_0.10-14.zip'
Content type 'application/zip' length 400799 bytes (391 Kb)
opened URL
downloaded 391 Kb
package
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
2010 Jun 10
1
glm poisson function
Hi,
I'm totally new to R so I apologise for the basic request. I am looking at
the incidence of a disease over two time periods 1990-1995 and 2003-2008. I
have counts for each year, subdivided into three disease categories and by
males/females.
I understand that I need to analyse the data using poisson regression and
have managed to use the pois.daly function to get age-sex adjusted rates and
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 Aug 25
1
Specifying random effects distribution in glmer()
I'm trying to figure out how to carry out a Poisson regression fit to
longitudinal data with a gamma distribution with unknown shape and
scale parameters.
I've tried the 'lmer4' package's glmer() function, which fits the
Poisson regression using:
library('lme4')
fit5<- glmer(seizures ~ time + progabide + timeXprog +
offset(lnPeriod) + (1|id),
data=pdata,
2008 Sep 23
3
odds ratio: how to create reference
HI there,
i know this is a basic question, though i need some help because this
is somewhat away from my current issue, but nevertheless interesting
to me... Lets assume i have some estimated probabilities, say
estimated by a logit model. i know i can also state them as an odds
ratio.
Now i?d like to state these odds ratios as a reference to a specific
outcome of my investigated
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
2010 Jul 05
2
Function to compute the multinomial beta function?
Dear R-users,
Is there an R function to compute the multinomial beta function? That is, the normalizing constant that arises in a Dirichlet distribution. For example, with three parameters the beta function is Beta(n1,n2,n2) = Gamma(n1)*Gamma(n2)*Gamma(n3)/Gamma(n1+n2+n3)
Thanks in advance for any assisstance.
Regards,
Greg
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