Demonstration of Bayesian error estimation according to Barlow (2003). Top panel: test profile. The signal-to-noise ratio of the continuum is 20. Center and bottom panels: histograms of the optical depth distribution, for the saturated absorption (center panel) and the narrower, unsaturated component (bottom panel). The dimidated Gaussians from models (1) and (2) are shown in red and blue, respectively, along with the asymmetric errors (arrows) and the asymmetry parameters α.