similar to: Power calculation

Hi, I am trying to do a power calculation for a difference in proportions test where I want to estimate the sample size required. I know (well estimate) that group one (n1) is 10% of the population and group 2 (n2) is 90% of the population. I know the effect size (h). pwr.2p2n.test only allows one variable to be left null whereas I would like both n1 and n2 to be determined where I know there

I have an unbalanced design I would like to run a power analysis on. What I have been able to find has pointed me to using the pwr.f2.test function as described below. My problem is that I don't know how to appropriately define the numerator and demoninator df. If someone can help here is some more info about my design. It is an unbalanced 2^3 x 3 design where the factor with 3 levels is a

Hi all, I'm having trouble getting access to the pwr. This is on Ubuntu Lucid Lynx, 64 bit. I'm installing pwr via packages.install('pwr'), and loading it via library(pwr), both of which appear successful. Strangely, I never get access to the pwr object in R. I tried installing it to /usr/local/lib/R/site-library and ~/R/x86_64-pc-linux-gnu-library. I also tried installing it

Dear R experts, I have conducted a power calculation in order to estimate the number of subjects needed to detect an effect size of d=0.28 (cohen's d) for a difference between two independent groups (alpha level should be 0.05 and the effect should be detected with 80% probability). The results from the code below indicates that I would need n=400 subjects (200 in each group). This is seems

Hello Using R 2.2.1 on a Windows machine. Has anyone programmed the Welch test for equality of variances? I tried RSiteSearch, but this gave references to t test and oneway.test, which are not quite what I need.....I need the Welch test itself, for use in a meta-analysis (to determine if variances are equal). TIA Peter Peter L. Flom, PhD Assistant Director, Statistics and Data Analysis

Hello, In one of the loop transformations I am developing, I need to convert eq and neq loop latch condition into less than or greater than depending on the control flow. The problem is that CmpInst::ICMP_EQ and CmpInst::ICMP_NE are neither signed nor unsigned in LLVM. Also, I did not find a way to find out if the integer operands of the CmpInst are signed or unsigned. Apparently, LLVM does

Is there a library that provides power calculation and sample size estimation for nonlinear regression? The task is easy for linear regression with the "pwr" package, but I can't find a method for nonlinear regression (estimated with the "nls" package). -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- Dr. Johannes W. Dietrich, M.D. --

Hello, I have 12 sample each sample has got 1000 observation, i.e I have a matrix X with 1000 rows and 12 columns! m <- svm(t(X)) p <- predict (m) Can anyone tell me how to use svmtrain() in R! Many Yhanks, Samuel [[alternative HTML version deleted]]

Hello, if we suppose that times <- c("2006-05-14", "2006-06-12", "2006-06-12", "2006-05-14", "2006-05-14", "2006-06-12") value <- c(2,3,1,4,3,1) then with plot(times, value) we have two boxplots in one graph for 2006-05-14 and 2006-06-12 respectively! Is it possible to have them in a scatterplot? and

Dear list, I got an automatic email complaining than some of my packages didn't pass 'R CMD check' for R-2.10.0 alpha anymore. Both of them make use of the "cases" LaTeX environment. Inspecting the log outputs I got: LaTeX errors when creating PDF version. This typically indicates Rd problems. LaTeX errors found: ! Misplaced alignment tab

Dear All I want to calculate power of test. I want to test H0: Rho = 0 VS H1: Rho != 0. Assume, I have r=0.2 and sample size = 100. How I can do this. Many Thanks Jumlong -- Jumlong Vongprasert Assist, Prof. Institute of Research and Development Ubon Ratchathani Rajabhat University Ubon Ratchathani THAILAND 34000 [[alternative HTML version deleted]]

Hello, I have got the following problem: > setwd("C:/temp") > library(xlsReadWrite) > MyData <- read.xls(file="Mappe1.xls", colNames = TRUE,dateTimeAs = "isodatetime") > attach(MyData) > MyData name value times 1 A1 2 2006-05-12 2 A2 3 2006-05-16 3 A3 1 2006-05-12 4 A4 4 2006-05-12 5 A5 2

Dear expeRts, What's a 'good' (nice-looking, easy-to-read) setup for the LaTeX package 'listings' to display R code? The two versions below are partly inspired by the settings of the package SweaveListingUtils and http://r.789695.n4.nabble.com/R-How-to-format-R-code-in-LaTex-documents-td816055.html Any suggestions, comments, or improvements are welcome. Cheers, Marius ###

I would like to code the following in R: a1(b1+b2+b3) + a2(b1+b3+b4) + a3(b1+b2+b4) + a4(b1+b2+b3) or in summation notation: sum_{i=1, j\neq i}^{4} a_i * b_i I realise this is the same as: sum_{i=1, j=1}^{4} a_i * b_i - sum_{i=j} a_i * b_i would appreciate some help. Thank you. -- View this message in context: http://r.789695.n4.nabble.com/summation-coding-tp4646678.html Sent from the R

Hello, I am trying to read the SAS file MyData.sa7bdat in R! This file is saved under D:\data! I therefore wrote > path <-"D:/SasData" > sashome <- "C/Progra, Files/SAS Institute/9_1/SAS" > sascmd <- file.path(sashome, "sas.exe") > MyData <- read.ssd(path, "MyData", sascmd=sascmd) The results what I get:

Full_Name: Michael J. Lew Version: R version 2.9.1 (2009-06-26) OS: OS X Submission from: (NULL) (210.49.195.149) The default function power.t.test gives inaccurate values, particularly with large sig.level. There are two reasons for me to propose that power.t.test is inaccurate: 1. When sig.level approaches 1, so should the power. However,

Greetings, I have stumbled across some unexpected behavior (potential a bug) in, what I suspect to be R's (2.6.2 on Ubuntu Linux) t.test function; then again the problem may exist in my code. I have shutdown R and started it back up, re-run the code and re-experienced the error. I have searched on Google for the abnormal termination error message "(stderr < 10 * .Machine$double.eps *

Hi all, I would like to estimate power and necessary sample size for a GLM with a response variable that has a poisson distribution. Do you have any suggestions for how I can do this in R? Thank you for your help. Sincerely, Craig -- Craig A. Faulhaber Department of Forest, Range, and Wildlife Sciences Utah State University 5230 Old Main Hill Logan, UT 84322 (435)797-3892

My apologies for the statistical naivete of my question but... Is there an established method or calulating the statistical power of a correlation test? And if so is there a method in R for it? Thank you, Collin Lynch.

I'm having trouble creating a looping variable and i can't see wher ethe problem arises from any hep gratfully appreciated First create a table x<-table(SURVEY$n_0,exposed) > x exposed False True Under 16 24 1 16-19 68 9 20-24 190 37 25-34 555 204 35-44 330 87 45-54 198 65 55-64 67 35 65+