error ellipse

A statistical measure of the positional error at a given point computed from the propagation of all errors contributing to the position and expressed by its semi-major and semi-minor axis and the covariance. Two-dimensional errors are typically propagated at one-standard deviation (39.4% probability that the position lies on or within the ellipse) or 2.1447 times the standard deviation (95% confidence) level.

A coordinate error ellipse is a graphical representation of the magnitude and direction of the error of network-adjusted points.