similar to: Looking for program for sample size determination

Craig, Thanks for your follow-up note on using the asypow package. My problem was not only constructing the "constraints" vector but, for my particular situation (Poisson regression, two groups, sample sizes of (1081,3180), I get very different results using asypow package compared to my other (home grown) approaches. library(asypow) pois.mean<-c(0.0065,0.0003) info.pois <-

Sorry, this is my first time to post. I have a big data set: first colume is date (ex: 2008-2-150, the second is time (10:30:00), and the following columes are variaty measurement data. Every 30 min, I have one data. I want to find an effecient way to calculate the hourly, daily, monthly and yearly average, and plot them, and eventually use these average data to do further analysis. Thanks!

I would like to do some power estimations for a log-rank two sample test and cpower seems to fit the bill. I am getting confused though by the man page and what the arguments actually mean. I am also not sure whether cpower takes into account censoring or not. Could anyone provide a simple example of how I would get the power for a set control/non-control clinical trial where censoring occurs at

Hello all, I don' like to have ( ) around my datetime, when send the csv file to somebody. How to remove it? >library(chron) >mydate <- c("2009-05-03","2009-06-07") >mytime <- c("10:30:00","10:20:00") >mydatetime <- chron(dates=mydate,times=mytime,format=c("y-m-d","h:m:s")) >write.csv(mydatetime)  

how to input multiple .txt files? A data folder has lots of .txt files from different customers. Want to read all these .txt files to different master files: such as: cust1.xx.txt, cust1.xxx.txt, cust1.xxxx.txt,.............. to master file: X.txt cust2.xx.txt, cust2.xxx.txt, cust2.xxxx.txt,.............. to master file: Y.txt Thanks! [[alternative HTML version deleted]]

Use  write.csv to output a zoo object, and found the first column in excel like:  (08-10-16 13:12:00)   How to make it look like : 10/16/2008 13:12:00 ?     write.csv(x=zoo.object)   Thanks! [[alternative HTML version deleted]]

I am trying to do power calculations for the proportional odds model using the asypow library. The code noncenta90b10<-asypow.noncent(theta.ha=a9010,info.mat=infomatrixa90b10,constraints=constrt) returns Error in max(..., na.rm = na.rm) : invalid "mode" of argument. the various arguments I've used are: a9010 [,1] [1,] -1.7357568 [2,] -0.1928619 specifying the

Hola! I got past the problems I asked about two days ago, thanks. No I am updating CRAN package asypow (the daily package check on CRAN gave warnings due to .Rd problems, fixed). Now it PASSED Rcmd check (WindowsXP home edition, rw2000dev, on a new toshiba laptop, if that matters.) but then Rcmd build --binary gives problems: . . . preparing package asypow for lazy loading Error in

Power calculations two sample test for proportions is very useful. Is there a way however, to get away from the two samples being of the same size. What would happen if one had n=15 in the one sample and n=45 in the other sample. Farrel Buchinsky, MD Pediatric Otolaryngologist Allegheny General Hospital Pittsburgh, PA **********************************************************************

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

Hi All Please see the Rprofile file which i have modified as follows and after that when I start R then I see that R says to me "TRUE" for all the packages implying that all loaded at once. But when i try to use commands as simple as help("lm"), it doesnt work nor any of the menu "Packages" is not working. Although the regression using lm ( Y ~ X ) is working

Hi everyone,I would like to test a mediation model, that has several control variables. More specifically, I would like to test the indirect effect with bootstrapping. However, all the packages I have found so far (e.g. MBESS) only allow testing a simple mediation model (One independent, one mediator, one dependent) so that I cannot include any controls. Can somebody help me? [[alternative HTML

Hello list I have a theoretical differential equation model (two coupled differential equations) describing the acidification of dairy cultures in milk: dX/dt = f(H, param)*X dH/dt = g(param)*dX/dt pH = -log10(H) I also have actual data of the same. I would like to estimate the parameters of the theoretical model from real data, but don't know how to go about it in R (I'm fairly new

Dear R fans ( and wiki fans), I am just writing a draft to introduce confidence intervals of various "effect sizes" to my students. Surely, I'll recommend the package MBESS in R. Currently, it means I have to recommend R's interface at first. As a statistics teacher in a dept of psychology, I often have to reply why not to teach SPSS. Psychologists and their students hate to

I'm in the process of porting a set of routines from S to R (the 'asypow' package) and have struck one or two problems that I've been unable to clear up with the documentation I have. I may simply need a pointer to the right docs. I managed to get the code to run with minimal changes, but in order to get it to load using library(), had to run it through: R CMD build ... and

Hello, I want to know if there are some functions or packages to solve differential and integral equation using R. Thanks. Shao chunxuan. [[alternative HTML version deleted]]

new R user has a question: I have several hundreds of .txt files from different monitoring sites over several years. (1) different site has a unique name( such as : ST2.20090321.txt = Sation 2 2009 March 21 data, ST3.20090322=Station3, 2009, March 22 data). (2) different site has different file header, but for the same site, the header is the same. for example: Sation 2 date time wind CO2

useR's, I am trying to do a power calculation for a survival analysis using a logrank test and I need some help properly doing this in R. Here is the information that I know: - I have 2 groups, namely HG and LG - Retrospective analysis with subjects gathered from archival data over 20 years. No new recruitment of subjects and no estimated time to target accrual and accrual rate. - Survival

Dear list, Is anyone aware of a library for sample size calculation in R, similar to NQuery? I have to give a course in this area, and I would like to enable the students playing around with this. Best wishes, Matthias

Hola, Estoy tratando de calcular el poder estadistico de un GLM en R, programas estadisticos como SPSS lo puede calcular pero no eh encotrado nada sobre R. Alguien tiene alguna idea o sabe de literatura donde pueda encontrar ayuda? Luego tengo otra pregunta mas bien teorica sobre la funcion offset utilizada en negative poisson, por lo que eh entendido esta funcion posibilita trabajar con