Robustness to redshift evolution in the SZ-mass scaling relation. The different contours show the constraints when relaxing the redshift evolution exponent, β, of Eq. (7). The black contours result from fixing β = 0.66, our fiducial value throughout, with α constrained by the Gaussian X-ray prior of Table 1. Applying a Gaussian the prior on β instead, from Table 1, produces the blue contours, while the red contours result when we also leave α free. In this figure we adopt the SZ+BAO+BBN data set and the CCCP mass bias prior.