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calculating area of ellipse?

To: s-news@lists.biostat.wustl.edu
Subject: calculating area of ellipse?
From: Bob Hilderbrand <rhilderbrand@al.umces.edu>
Date: Fri, 16 Feb 2007 16:10:22 -0500
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Hi all, I'm generating bivariate confidence ellipses using the car library. I would also like to calculate the area of the ellipse, but cannot figure out how. ||Specifically, I'm using the data.ellipse function where I feed it my X and Y data and desired confidence level. I cannot figure out within the function (or the function ellipse which is called from data.ellipse) which variables represent the dimensions of the major (a) and minor (b) axes, assuming they have already incorporated correlation between X and Y. If I can get those, then the area is easy (pi * a * b). It's probably easy, but it's got me stumped. Any suggestions or alternative approaches would be greatly appreciated. Thanks, bob

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