> Hello,
> I wonder if anyone has a function for calculating confidence intervals for
> ratios. I have mortality rates calculated for several groups from sample
> data -- but these can be treated as ratios?).
Do you mean a conficence interval for a ratio parameter (e.g. ratio of
means) or for measurements that are defined as ratios?
In the first case the exp of the t.test conf ints of the log-transformed
data can be used (under the assumption of log-normality):
R> x <- rlnorm(20)
R> y <- rlnorm(20)
R> exp(t.test(log(x),log(y),var.equal=TRUE)$conf.int)
[1] 0.7530694 3.5936215
attr(,"conf.level")
[1] 0.95
(works with wilcox.{test,exact} for the ratio of medians, too).
In the second one, you'll probably have to think about the parameter to
calculate confidence intervals for ...
Torsten
> I am entertaining the idea of
> bootstrapping them.
> Any help would be greatly appreciated.
> TIA, Marwan
>
>
>
----------------------------------------------------------------------------
> ------------
> Marwan Khawaja - http://departments.aub.edu.lb/~mk36/ If you have MS
> Internet Explorer!
>
----------------------------------------------------------------------------
> ------------
>
>
-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-
> r-help mailing list -- Read http://www.ci.tuwien.ac.at/~hornik/R/R-FAQ.html
> Send "info", "help", or "[un]subscribe"
> (in the "body", not the subject !) To: r-help-request at
stat.math.ethz.ch
>
_._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._
>
-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-
r-help mailing list -- Read http://www.ci.tuwien.ac.at/~hornik/R/R-FAQ.html
Send "info", "help", or "[un]subscribe"
(in the "body", not the subject !) To: r-help-request at
stat.math.ethz.ch
_._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._