Displaying 20 results from an estimated 4000 matches similar to: "Permutation or Bootstrap to obtain p-value for one sample"
2009 Feb 02
1
A question regarding bootstrap
Dear List Members,
I have two small samples (n=20), the distributions are highly skewed. Does
it make any sense to do a boostrap test to check for difference in means?
And if so, could this be done like this:
x <- numeric(10000)
for(i in 1:10000) {
x[i] <- mean(sample(sample1,replace=TRUE)) -
mean(sample(sample2,replace=TRUE))
}
(mean(sample1)-mean(sample2))/sd(x)
Regards,
Erika
2011 Jul 12
1
Quantitative Analyst/Quantitative Developer
Hello,
I would like to post the below position on your site.
Thanks,
Quantitative Analyst/Quantitative Developer
MSIM Global Risk & Analysis, Quantitative Research & Model Review group
Morgan Stanley Investment Management (MSIM), together with its investment advisory affiliates, has more than 680 investment professionals around the world and approximately $279 billion in assets under
2011 Mar 15
2
Calculate monthly means
I am trying to calculate monthly means by year of phosphates and nitrates from a multi year data set. Can anybody help me out with the most effective way to do this?
My data looks like this:
Collection_Date Test.Name Value
2000-01-24 17:00:00 Phosphate 0.108
2000-01-24 17:00:00 Nitrate 0.037
2001-11-12
2012 Apr 26
1
Heatmap fidelity
I'm having a problem when using heatmap. Even though the diagonal of my
matrix is all the same value, the diagonal of my heatmap is not all the same
color. Any suggestions?
Here is some reproducible code:
#########################################
# Get data
nba <- read.csv("http://datasets.flowingdata.com/ppg2008.csv", sep=",")
# Reorder
nba <-
2002 Dec 12
2
t-test bootstrap versus permutation question
Hi,
I have a little problem that puzzles me about contradictory results returned
by a bootstraped t-test (as in MASS 3rd ed p. 146) versus a permutation
t-test (as in MASS 3rd ed, p 147).
Data are measurements done on 100 cells in 9 slides of fish blood. With one
method, cells are randomly sampled, and with the other method, the operator
selects cells arbitrarily (in a way it is done usually
2005 Apr 23
1
Bootstrap / permutation textbooks
Dear R experts,
I would like to explore if and to what extent bootstrapping and
permutation statistics can help me for my research (functional brain
imaging). I am looking for an introductory textbook, rather legible. I
have statistical knowledge, but I am definitely no statistical or
mathematical guru.
Do you have suggestions for a useful textbook?
Thanks a lot,
Peter
2012 Apr 12
2
pyramid.plot in plotrix, axis labelling
Hi, I've been looking at ways to make pyramid plots in R. I like the pyramid.plot method in plotrix as it seems the simplest to use and building them in ggplot looks a bit more code intensive than I'd like, being as I'm new to R. This package does pretty much what I need it to do, however I can't seem to scale the x axis labels. The other labels scale fine with labelcex.
I
2008 Jul 26
4
parametric bootstrap
Hi
I am trying to find a parametric bootstrap confidence interval and when I used the boot function I get zero bias and zero st.error? What could be my mistake?
Thank you and take care.
Laila
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2001 Aug 28
2
Christmas tree graphs
Hello R users,
I wish to draw a type of horizontal bar chart for two groups (males and
females). The values for one group will start at the y-axis and point to the
left, and the values for the other group will start at the y-axis and point to
the right. If you're (un)lucky, the resulting graph can assume the shape of a
Christmas tree.
The data are
left.side <- c(107092, 113053,
2004 Mar 30
1
classification with nnet: handling unequal class sizes
I hope this question is adequate for this list
I use the nnet code from V&R p. 348: The very nice and general function
CVnn2() to choose the number of hidden units and the amount of weight
decay by an inner cross-validation- with a slight modification to use it
for classification (see below).
My data has 2 classes with unequal size: 45 observations for classI and
116 obs. for classII
With
2004 Dec 17
2
Doubts about chi-square distribution
Dear list,
For educational purposes I have been working with the script below.
I have a observation:
line 31
#CScal[i] = (amo^2) # IT IS WRONG, I KNOW, BUT IT MAKE R TO CRASHES!
I'm thinking this is a possible bug in the R!
And I have a couple of doubts:
1) line 51
#curve(dchisq(x, n-1), add = T, col = 'red'
I think that it is correct, but the function no
2006 Sep 27
3
Converting text to numbers
Hi,
I have Forecast Class and Observed Class in a data matrix as below.
> Sample1
FCT OBS
1 1 5
2 2 4
3 3- 3+
4 3 3
5 3+ 3-
6 4 2
7 5 1
I want to find the difference between Observed and Forecast Classes.
How can I get this done?
I tried to following to convert the 1 through 5 classes, to 1 through 7
for both OBS and FCT column.
> Sample1$OBS2 <- Sample1$OBS
2012 Dec 04
2
computing marginal values based on multiple columns?
Hello all,
I have what feels like a simple problem, but I can't find an simple
answer. Consider this data frame:
> x <- data.frame(sample1=c(35,176,182,193,124),
sample2=c(198,176,190,23,15), sample3=c(12,154,21,191,156),
class=c('a','a','c','b','c'))
> x
sample1 sample2 sample3 class
1 35 198 12 a
2 176 176
2012 Jan 25
4
help to slip a file name using "strsplit" function
Dear Researchers,
I have several files as this example: Myfile_MyArea1_sample1.txt
i wish to split in "Myfile", "MyArea1", "sample1", and "txt", becasue i
need to use "sample1" label. I try to use "strsplit" but I am able just to
split as "Myfile_MyArea1_sample1" and "txt" OR "Myfile", "MyArea1",
2012 Jul 17
1
Different LDAP filters for different protocols
Is it possible to query LDAP differently for different protocols? I am
using dovecot for both pop3/imap and lmtp deliveries and there are
different enable flags in ldap for them. I tried wrapping user_filter
inside the protocols in the file dovecot-ldap.conf.ext as shown below but
this didn't seem to work.
protocol lmtp {
user_filter =
2012 Jul 31
2
phantom NA/NaN/Inf in foreign function call (or something altogether different?)
Dear experts,
Please forgive the puzzled title and the length of this message - I
thought it would be best to be as complete as possible and to show the
avenues I have explored.
I'm trying to fit a linear model to data with a binary dependent
variable (i.e. Target.ACC: accuracy of response) using lrm, and
thought I would start from the most complex model (of which
"sample1.lrm1" is
2008 Apr 15
1
sign(<permutation>) in R ?
I am looking for an algorithm (written in R (preferably) or C,
but even pseudo-code in a text book maybe fine)
to determine the sign of a permutation.
What is that? Well, a permutation is either even or odd, the
sign is +1 or -1, respectively, see, e.g.,
http://en.wikipedia.org/wiki/Signature_of_a_permutation
which also says
>> In practice, in order to determine whether a given
2019 Sep 12
2
Gnu sieve vs Dovecot sieve-filter - sieve-filter extremely slow at lda (writing emails to local mbox files)
I am wondering why sieve-filter is so slow compared to gnu sieve.
I run mpop (like getmail) to download from a pop3 server to a local
mbox file: ~/mail/email-incoming-unsorted
This step is very fast.
The next step, I throw the email-incoming-unsorted mbox file at a
sieve processor, to sort the emails from that mbox, into other
mboxes, according to the sieve rules file.
Up until a couple days
2011 Sep 17
2
onet.permutation()
I saw the manual of this function but not sure what to do.
I have a array contain 7 numbers and want to choose 4 to do permutation
test. But using this function with parameters as onet.permutation(scores,4),
it returns 0. Instead, with no parameter, onet.permutation(), it returns
something but every time it's different.
Please tell me how am I supposed to do it.
Thanks a lot
--
View this
2018 May 23
2
find the permutation function of a sorting
Hi,
Is there any way to find the permutation function of the sorting and to
apply the function (or its inverse) elsewhere?
For example, the following permutation function from the sorting in the
matrix form is
c(1,2,3), c(2,1,3)
> sort(c("bc","ac","dd"))
[1] "ac" "bc" "dd"
I try to find it in the permutations/permute