similar to: Formula of power.t.test

Dear all I am very beginner user of R I want to calculate the power of t-test using power.t.test function. It is stated in the manual that the argument (n) is the number of observations per group. Infact I have a differens number of observations in each group(ie n1<>n2) and another thing is SD the pooled standard deviation of the observations in the two data sets under investigation. Hope

Something like the following should be done for power.t.test to make sure that it doesn't try to evaluate abs(NULL), which results in an error. --- rossini.power.t.test.R 2003-05-30 07:24:49.000000000 -0700 +++ rossini.power.t.test.R.~1~ 2003-05-30 08:47:09.000000000 -0700 @@ -10,7 +10,7 @@ alternative <- match.arg(alternative) tsample <- switch(type, one.sample = 1,

Hi, I am trying to read data from Microsoft SQL. I tried to use odbcConnect (in RODBC) but failed. What should the "dsn" be? Does anyone know how to do it? I will appreciate it. Thank you! Xiaorong ________________________________________________________________________ The preceding e-mail message (including any attachments) contains information that may be confidential, be

What is the rationale behind having both the delta and sd parameters for the power.t.test function? For the relevant noncentrality parameter, we only need the ratio delta/sd. If my effect size is given as Cohen's d, then I only got that ratio and not sd. As far as I see, in such a case, I can specify delta=d and leave sd at its default value 1. Is this correct or am I missing something?

Greetings, I've tried to update the power.t.test function to allow for different sample sizes and sample variances in the case of a two-sample t test. I'd gladly update the corresponding help page if the code is to replace the current power.t.test function. The modified power.t.test code is included below. The changes are as follows: - Added three new arguments to the function *

It's the same as PR#2993, fixed yesterday in R-patched & R-devel On Fri, 30 May 2003 rossini@blindglobe.net wrote: > > Something like the following should be done for power.t.test to make > sure that it doesn't try to evaluate abs(NULL), which results in an > error. That's a backwards patch, I presume, or you revert the fix. > --- rossini.power.t.test.R

Greetings all, I'm trying to figure out how to calculate the inverse CDF (i.e. a quantile) for a non-central F distribution. I could put together a quick numerical solver routine using the CDF, but I wonder if there's a function that I've missed that would be more efficient? Thank-you, Andrew Andrew Robinson Ph: 208 885 7115 Department of Forest Resources Fa: 208 885

Dear all I am trying to calculate the value of n using uniroot. Here is the message I am having: <<< Error in uniroot(integ, lower = 0, upper = 1000, n) : 'interval' must be a vector of length 2 >>> Please would you be able to give me an indication on why I am having this error message. Many thanks EXAMPLE BELOW: ## t = statistics test from t -distribution

Hi, I am trying to sort out a discrepancy between power calculations results between me and another statistician. I use R but I am not sure what she uses. It is on the proportions test and so I have been using pwr.prop.test. I think I have tracked the problem down to pwr.prop.test not using the continuity correction for the test (I did this by using the java applet from

hello R-friends, I'm looking for a quantile function for the noncentral f-distribution in the area of equivalence hypotheses testing. Can somebody help me? Many thanks ----------------------------------------------------------------- Dipl. Inform. J. Hedderich Institut f?r Medizinische Informatik Phone : 0431 / 5973182 und Statistik im Klinikum an der CAU

Dear all, Could any one please tell me the exact formula R uses to calculate the sample size for one-sample and two-sample t-tests? Thanks, Caimiao [[alternative HTML version deleted]]

Dear R-users, I am wondering whether R implements a function returning the non central parameter of a t distribution (equivalent of the TnoncT function from SAS), given /x/ a value from a t distribution, /df /the degrees of freedom and /p/ the probability of x under this distribution. Thanks a lot, Matthieu -- Matthieu Dubois, /Ph.D/. /Student/ Cognitive Neuroscience Unit, UCL,

Dear Sir/Madam, I am doing a project related to R. However, it is always difficult find some R functions. The R user guide seems not complete. Is there any free document about all R functions ? Who knows ? please help me. My email is myzhaogong@yahoo.com Thank you very much --------------------------------- [[alternative HTML version deleted]]

Respected Sir/Madam, As I was developing some part of compiler for a project. I require grammar (BNF or EBNF) for converting the C code in the IR as it is not been mentioned any where over your official website. Awaiting for your help. Regards, Vijay Daultani. M.Tech student IIT Delhi

Respected sir/madam can you please suggest what is an unexpected symbol in the below code for running a multinomial logistic regression model <- multinom(adoption ~ age + education + HH size + landholding + Farmincome + nonfarmincome + creditaccesibility + LHI, data=newdata) [[alternative HTML version deleted]]

Dear Sir/Madam, I am using R version 1.8.1. I am doing following tast: First generate 100 Gaussion(3,1) numbers, then write the likelihood function to estimate the parameters of Gaussian distribution by direct maximizing the likelihood function. My likelihood function is: >fn<-function(x) >(-50*log((sd(x))^2))-50*log(sqrt(2*pi))-(1/2*((mean(x))^2))*(sum((x-(mean(x))^2)) After I

Every now and then I get an alert like this one. I have no clue what this "rear" subsystem is, or why madam would be trying to write to its log file. Can anyone enlighten me? thanks in advance! ------------------------- SELinux is preventing /usr/sbin/mdadm from write access on the file /var/log/rear/rear-fcshome.log.lockless. ***** Plugin restorecon (93.9 confidence) suggests

Hi everyone. I have a problem that I have been unable to determine either the best way to proceed and why the methods I'm trying to use sometimes fail. I'm using the pf() function in an optimization function to find a noncentrality parameter that leads to a specific value at a specified quantile. My goal is to have a general function that returns the noncentrality parameter that

Hallo sir/madam, I have a Chinese brand Ultrasound unit Ivis 60 model which had issues with booting after power fluctuations here in Congo -Africa. It is using a syslinux 3.31 which is continually giving problem when trying to enter BIOS so that I can install new files available on the usb disk. To enter bios you have to continually press "delete button" when starting the unit but no

Does anybody has a function or idea how to calculate qt with a noncentrality parameter? I'm porting a SAS-macro for equivalence (Wellek, 1994 TT2ST) to R and it seems that I need this to calculate tinv (SAS-command, I hope that this is R's qt,...I get the SAS-macro manual next week). thanks Peter -- P.Malewski, Limmerstr.47, 30451 Hannover, 0511-2135008 At work: