Displaying 15 results from an estimated 15 matches for "albyn".

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2011 Apr 18

3

Power Analysis

I am trying to do a power analysis to get the number of replicas per
treatment.
If I try to get the power it works just fine:
setn=c(2,3)
sdx=c(1.19,4.35)
power.t.test(n = setn, delta = 13.5, sd = sdx, sig.level = 0.05,power =
NULL)
If I go the other way to obtain the "n" I have problems.
sdx=c(1.19,4.35)
pow=c(.8,.8)
power.t.test(n = NULL, delta = 13.5, sd = sdx, sig.level = 0.05,

2010 May 10

1

Random walk

Hi everybody,
I am trying to generate two random walks with an specific correlation,
for example, two random walks of 200 time steps with a correlation 0.7.
I built the random walks with:
x<-cumsum(rnorm(200, mean=0,sd=1))
y<-cumsum(rnorm(200, mean=0,sd=1))
but I don't know how to fix the correlation between them.
With white noise is easy to fix the correlation using the function

2011 May 27

2

"useR! 2011" T-shirt competition

Dear R users:
We are looking for a new design for the front of the "useR! 2011"
conference T-shirt, and we invite submissions by June 13.
It is planned that participants in the R User Conference, useR! 2011
(August 16-18, http://R-project.org/useR-2011) will each receive a
T-shirt, thanks to the sponsorship of Mango Solutions

2010 Dec 02

4

Integral of PDF

The integral of any probability density from -Inf to Inf should equal 1, correct? I don't understand last result below.
> integrate(function(x) dnorm(x, 0,1), -Inf, Inf)
1 with absolute error < 9.4e-05
> integrate(function(x) dnorm(x, 100,10), -Inf, Inf)
1 with absolute error < 0.00012
> integrate(function(x) dnorm(x, 500,50), -Inf, Inf)
8.410947e-11 with absolute error <

2013 Aug 30

4

mean

When I try to apply mean to a list, I get the answer :
argument is not numeric or logical: returning NA
Could you help me?
(I am a very beginner)
--
View this message in context: http://r.789695.n4.nabble.com/mean-tp4674999.html
Sent from the R help mailing list archive at Nabble.com.

2013 May 23

1

sample(c(0, 1)...) vs. rbinom

Greetings.? My wife is teaching an introductory stat class at UC Davis.? The
class emphasizes the use of simulations, rather than mathematics, to get
insight into statistics, and R is the mandated tool.?? A student in the class
recently inquired about different approaches to sampling from a binomial
distribution.? I've appended some code that exhibits the idea, the gist of
which is that using

2002 Oct 09

1

Summary Orthogonal Polynomials

As usual, the R newsgroup set me straight (thanks to Douglas Bates, Robert
Balshaw and Albyn Jones).
There is really no difference between using orthogonal polynomials of the
form:
Linear -3 -1 1 3
Quadratic 1 -1 -1 1
Cubic -1 3 -3 1
Versus
> poly(c(1:4),3)
1 2 3
[1,] -0.6708204 0.5 -0.2236068
[2,] -0.2236068 -0.5 0.6708204
[3,] 0....

2010 Sep 13

2

The future of R - Ross Ihaka stirs discussions around the web

Hello all,
There is currently a (very !) lively discussions happening around the
web, surrounding the following topics:
1) Is R efficient? (scripting wise, and performance wise)
2) Should R be written from scratch?
3) What should be the license of R (if it was made a new)?
Very serious people have taken part in the debates so far. I hope to let
you know of the places I came by, so you might be

2006 Jun 19

1

Foometrics in R

One of the outcomes of useR! 2006 is that JSS is planning to publish
a series of special volumes. They will be guest edited (I have guest
editors already, although somewhat tentative in some cases). Each volume
will have 5-10 issues (articles) of the usual JSS format.
Psychometrics in R
Political Methodology in R
Econometrics in R
Social Science Methodology in R
Spectroscopy/Chemometrics in R

2008 Dec 19

1

comparing distributions

I have data sets from three different sites. None of the data sets are
normally distributed and can not be log-transformed to a normal
distribution. I would like to compare the data sets to see if any of
the sites are similar to each other, and would like something more
powerful than a non-parametric wilcoxen test. Does anyone have any
suggestions on more powerful ways of comparing non-normal data

2011 Aug 19

3

Calculating p-value for 1-tailed test in a linear model

Hello,
I'm having trouble figuring out how to calculate a p-value for a 1-tailed
test of beta_1 in a linear model fit using command lm. My model has only 1
continuous, predictor variable. I want to test the null hypothesis beta_1
is >= 0. I can calculate the p-value for a 2-tailed test using the code
"2*pt(-abs(t-value), df=degrees.freedom)", where t-value and degrees.freedom

2009 Feb 28

3

Extract statistics from lm()

Hi, perhaps this question was answered previously however I could not find
them. My problem is how how to extract a particular statistic from the
result given by lm(). For e.g.
ctl <- c(4.17,5.58,5.18,6.11,4.50,4.61,5.17,4.53,5.33,5.14)
trt <- c(4.81,4.17,4.41,3.59,5.87,3.83,6.03,4.89,4.32,4.69)
group <- gl(2,10,20, labels=c("Ctl","Trt"))
weight <- c(ctl, trt)
>

2009 Jul 30

4

truncating values into separate categories

Hi all,
Simple question which i thought i had the answer but it isnt so simple for
some reason. I am sure someone can easily help. I would like to categorize
the values in NP into 1 of the five values in "Per", with the last
category("4") representing values >=4(hence 4:max(NP)). The problem is that
R is reading max(NP) as multiple values instead of range so the

2009 Mar 10

5

Cholesky Decomposition in R

Hi everyone:
I try to use r to do the Cholesky Decomposition,which is A=LDL',so far I
only found how to decomposite A in to LL' by using chol(A),the function
Cholesky(A) doesnt work,any one know other command to decomposte A in to
LDL'
My r code is:
library(Matrix)
A=matrix(c(1,1,1,1,5,5,1,5,14),nrow=3)
> chol(A)
[,1] [,2] [,3]
[1,] 1 1 1
[2,] 0 2 2

2001 Sep 03

8

mixture distributions

Dear List,
I am looking for a possibility to fit a mixture model under R using
maximum likelihood estimation.
Venables and Ripley describe a solution working under S+ (in MASS, 3. ed.,
p. 263) which requires the D system function and deriv3. This solution does not
seem to be portable to R or at least I do not realise how.
Is there anyone who
a) knows how one could make the MASS-method run under