# Thread: Bivariate Contour Ellipse Area

1. ## Bivariate Contour Ellipse Area

I have found a research paper, where there is need to calculate the area of a bivariate contour ellipse. I am familiar with drawing a confidence ellipse, so my concern is about the formulas provided in this publication.
As it is mentioned the bivariate contour ellipse area is calculated with the following formula:

(1)
where is the product moment correlation coefficient and are the standard deviations of the two variables.

It also states that k can be calculated through probability equation
(2)

I need help to understand which probability function is equation (2) and how we get as outcome for the area calculation equation (1)