[R] calculating area of ellipse

John Fox j|ox @end|ng |rom mcm@@ter@c@
Thu May 6 21:06:45 CEST 2021


Dear James,

To mix notation a bit, presumably the (border of the) confidence ellipse 
is of the form (b - beta)'V(b)^-1 (b - beta) = c, where V(b) is the 
covariance matrix of b and c is a constant. Then the area of the ellipse 
is pi*c^2*sqrt(det(V(b))). It shouldn't be hard to translate that into R 
code.

I hope this helps,
  John

John Fox, Professor Emeritus
McMaster University
Hamilton, Ontario, Canada
web: https://socialsciences.mcmaster.ca/jfox/

John Fox, Professor Emeritus
McMaster University
Hamilton, Ontario, Canada
web: https://socialsciences.mcmaster.ca/jfox/

On 2021-05-06 7:24 a.m., james meyer wrote:
> In doing meta-analysis of diagnostic accuracy I produce ellipses of confidence
> and prediction intervals in two dimensions.  How can I calculate the area of
> the ellipse in ggplot2 or base R?
> 
> thank you
> James Meyer
> 
> ______________________________________________
> R-help using r-project.org mailing list -- To UNSUBSCRIBE and more, see
> 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.
>



More information about the R-help mailing list