Significance of the dipole for the three error-estimation methods. For a given dipole amplitude, method (1) yields the smallest errors and thus the highest significance (red dot-dashed line), followed by method (2) (black solid line). Method (3), rotations of the actual cluster template, creates the by far largest uncertainties and thus assigns the lowest significance. Both method (1) and (2) were applied to 359 realizations of a random cluster template or a simulated CMB sky, respectively, in order to match the fixed statistics of 359 rotations provided by method (3).