similar to: Statistical Power

Is there an R package available that would facilitate doing a power/sample size analysis for linear mixed effects models? I have seen the Java applets made available by Russell Length which would seem to be able to handle most any lme, but there is little documentation and it's not clear how the models need to be formulated. Rick B.

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I remember reading about post hoc statistical power on R-help. But I can't seem to find them with RSiteSearch("post hoc statistical power") and variations of it. I would like to learn more about post hoc statistical power, its meaningfulness, advantages and disadvantages. I thought the issue was settled after Tukey's 1993 paper about post hoc statistical power being

Dear R helpers, I have a question about drawing random numbers from many categorical distributions. Consider n individuals, each follows a categorical distribution defined over k categories. Consider a simple case in which n=4, k=3 as below catDisMat <- rbind(c(0.1,0.2,0.7),c(0.2,0.2,0.6),c(0.1,0.2,0.7),c(0.1,0.2,0.7)) outVec <- rep(NA,nrow(catDisMat)) for (i in 1:nrow(catDisMat)){

Hi there, I have a binary matrix (dim 100x100) filled with values 0 and 1. I need select a record "n" positions of that matrix when values are 1. How can I do that? Thanks for all, Miltinho Brazil --------------------------------- [[alternative HTML version deleted]]

# is there a bug in the calculation of the odds ratio in fisher.test? # Nicholas Horton, nhorton at smith.edu Fri Jan 22 08:29:07 EST 2010 x1 = c(rep(0, 244), rep(1, 209)) x2 = c(rep(0, 177), rep(1, 67), rep(0, 169), rep(1, 40)) or1 = sum(x1==1&x2==1)*sum(x1==0&x2==0)/ (sum(x1==1&x2==0)*sum(x1==0&x2==1)) library(epitools) or2 = oddsratio.wald(x1, x2)$measure[2,1] or3 =

I have hundreds of humans who have undergone SNP genotyping at hundreds of loci. Some have even undergone the procedure twice or thrice (kind of an internal control). So obviously I need to find those replications, and confirm that the results are the same. If there is discordance then I need to address it. I tried to use the aggregate function nr.attempts

here appears to be a bug in the foreign library. The following code used to work, but now generates an error when 'package="SAS"' is specified: ds <- read.csv("http://www.math.smith.edu/sasr/datasets/help.csv") # running foreign package version 0.8-30 library(foreign) # this works fine write.foreign(ds, "foo", "bar", package="Stata") #

Hello all again, I want to do bitwise addition in R. I am trying to generate a matrix 0000 0001 0010 .... .... 1111 I know the other ways of generating this matrix but I need to look at bitwise addition. Any suggestions??? thanks a lot Nameeta ------------------------------------------------- This email is intended only for the use of the individual or...{{dropped}}

?"=", ?"==", ?"!=", ?">=", and ?"<=" sends me to the documentation for ?help on Windows, while returning the correct documentation on Linux. Robert > version _ platform i386-pc-mingw32 arch i386 os mingw32 system i386, mingw32 status major 2 minor

Dear list members, Could anyone tell me if there is an equivalent of the Matlab declaration 'persistant' in R? Thank you very much, Bernard Gregorry. (Matlaber converted to R). --------------------------------- [[alternative HTML version deleted]]

dear all, in the package pwr , there is the fonction power.anova.test which permit to obtain the power for a one-way ANOVA...but I'm looking for a way to compute the power of a multiway ANOVA.( find the 1-beta). Is it possible? do you have some ideas ? regards [[alternative HTML version deleted]]

Hello everybody I have done a generalized linear model (glm-function) with a binary response variable (presence/absence) and two explanatory variables (including the interaction term (model<-glm(x~factor1*factor2, family=quasibinomial)). The interaction is what we are mainly interested in and it is non-significant (F=0, p=1.0). A reviewer on the manuscript now asks for a a priori

Dear Colleagues: I would like to write a front end for a modeling function, but run into trouble when passing a weights argument. y <- 1:5 x <- c(1,3,2,5,4) w <- function(formula, ...) lm(formula, ...) lm(y ~ x, weights=c(1,1,1,2,2)) w(y ~ x) w(y ~ x, weights=c(1,1,1,2,2)) Error in eval(expr, envir, enclos) : ..1 used in an incorrect context, no ... to look in w <-

I have a case-control study that I'm analysing using the conditional logistic regression function clogit from the survival package. I would like to calculate the AICc of the models I fit using clogit. I have a variety of scripts that can calculate AICc for models with a logLik method, but clogit does not appear to use this method. Is there a way I can calculate AICc from clogit in R? Many

Dear All: I try to use latex expression in legend, but I am not very clear on the detail rules in R. I remeber there is a R help page list all rules and many examples, but I forget what should I type (?xxx) to get this help page. Could you please remind me which function should I type? Thanks _________________________________________________________________ Find a local pizza place, music

Hello! I am new to R. I could not find a function analogous to matlab's function buffer, which is used in signal processing. Is there such a function in R? What I need to do is as follows. If I apply the function to the vector c(1:5) for example with a window length 3 and overlapping 2, I need to get a matrix like this: 1 2 3 2 3 4 3 4 5 In matlab this is achieved with the function buffer. Is

Hi, I was wondering if anyone is aware of an R interface to ImageMagick (www.imagemagick.org)? Since R does not support a lot of image processing functions, having such an interface could be very useful. Alternatively, ImageMagick has a couple of different interfaces (including to C and C++). I was wondering if one can use these to call ImageMagick functions from R. I am posting a similar

Hi All I had to assure the randomness of backgammon game's two dices. I took 8,000,000 observations and found that one of the dices is not uniform distributed. I took 80,000,000 observations and found that the dice is uniform distributed. In both tests I used Pearson Chi Square test. My questions: 1. How many observations should I take? 2. How much the 80,000,000

Hi Folks! I need to execute a piece of R code inside a loop, say, every fourth time my counter increases (it increases by 1 unit each time.) Is there any sort of mod function in R to do this? Or is this done some other way? Many thanks! Best, john [[alternative HTML version deleted]]