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
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