Hi On 19 Oct 2006 at 13:19, Ethan Johnsons wrote:
Date sent: Thu, 19 Oct 2006 13:19:40 -0400 From: "Ethan Johnsons" <[EMAIL PROTECTED]> To: "Chuck Cleland" <[EMAIL PROTECTED]> Copies to: r-help@stat.math.ethz.ch Subject: Re: [R] CI with sd > I thought of another interesting scenario, and I would just go ahead > and ask this. I have a mean (i.e. 26.2) where the number of e coli > samples is 250. The mean is already calculated, so it is a discrete > value, not series. > > What fucntion can be used for the calc with CI i.e. 90%? With some sd value and assuming normal distribution 26.2+qnorm(.95)*sd/sqrt(250) 26.2-qnorm(.95)*sd/sqrt(250) as you can find in statistical textbooks. But without having sd value? HTH Petr > > thx much, > > ej > > On 10/19/06, Chuck Cleland <[EMAIL PROTECTED]> wrote: > > Ethan Johnsons wrote: > > > Please let me ask you another quick question. > > > I have results for e coli, and am trying to get 95% CI with the sd > > > (1.783956). I got the result from another tool as (1.21, 3.42). > > > But, I like to verify it with R. What function do you use for > > > this? > > > > > >> e.coli=c(27.5,24.6,25.3,28.7,23,26.8,24.7,24.3,24.9) > > >> sd(e.coli, na.rm = FALSE) > > > [1] 1.783956 > > > > > > Sorry for the newbie question. > > > > e.coli <- c(27.5,24.6,25.3,28.7,23,26.8,24.7,24.3,24.9) > > library(nlme) > > mod1 <- gls(e.coli ~ 1) > > intervals(mod1) > > > > Approximate 95% confidence intervals > > > > Coefficients: > > lower est. upper > > (Intercept) 24.16206 25.53333 26.90460 > > attr(,"label") > > [1] "Coefficients:" > > > > Residual standard error: > > lower est. upper > > 1.204986 1.783956 3.417651 > > > > > thx much > > > > > > ej > > > > > > ______________________________________________ > > > R-help@stat.math.ethz.ch mailing list > > > https://stat.ethz.ch/mailman/listinfo/r-help > > > PLEASE do read the posting guide > > > http://www.R-project.org/posting-guide.html and provide commented, > > > minimal, self-contained, reproducible code. > > > > -- > > Chuck Cleland, Ph.D. > > NDRI, Inc. > > 71 West 23rd Street, 8th floor > > New York, NY 10010 > > tel: (212) 845-4495 (Tu, Th) > > tel: (732) 512-0171 (M, W, F) > > fax: (917) 438-0894 > > > > > > ______________________________________________ > R-help@stat.math.ethz.ch mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide > http://www.R-project.org/posting-guide.html and provide commented, > minimal, self-contained, reproducible code. Petr Pikal [EMAIL PROTECTED] ______________________________________________ R-help@stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.