Significance of the preference for a dipole+monopole model over the monopole model versus number of data points clipped. At each step we have removed the absorber with smallest weighted residual ξ/cosθ, where θ is the angle between the location of the absorber and the dipole axis. Solid line: significance assessed using F-test; dashed line: significance assessed using EEM. The vertical dashed line indicates the point at which the dipole model is not preferred according to the AIC_c.