Figure 4

Elliptical confidence limits. The outer ellipse delineates the 95% confidence region for the joint estimation of the amplitude and acrophase (as a pair). Distances and tangents drawn from the pole to this outer ellipse yield conservative 95% confidence limits for the amplitude and acrophase considered separately as the area thus delineated is larger than the area of the outer ellipse. In order to obtain separate 95% confidence limits for the amplitude and acrophase, distances and tangents need to be drawn to a somewhat smaller (inner) ellipse. For further details, see [43]. © Halberg Chronobiology Center.