search for: albyn

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