Re: [R] calculating area of ellipse

Hi John, Thanks for that. An education for me and my advice to use "str" to check for the radii in the return value was clearly mistaken. Jim On Sat, May 8, 2021 at 2:15 AM John Fox wrote: > > Dear David and Jim, > > As I explained yesterday, a confidence ellipse is based on a quadratic > form

Re: [R] calculating area of ellipse

Dear David and Jim, As I explained yesterday, a confidence ellipse is based on a quadratic form in the inverse of the covariance matrix of the estimated coefficients. When the coefficients are uncorrelated, the axes of the ellipse are parallel to the parameter axes, and the radii of the ellips