Scaled profiles and scatter. Left: median scaled profiles (solid lines) and 68% scatter (envelopes) for REXCESS and the SZE-selected sample split into three redshift bins. Beyond ∼0.2 R₅₀₀ the scaled profiles are almost indistinguishable. Right: radial profile of the intrinsic scatter for the various sub-samples. The best-fitting intrinsic scatter model obtained from the SZE-selected sample is also shown. Intrinsic scatter is less than 20% between 0.2 ≲ R₅₀₀ ≲ 1.0. The gold line shows the model intrinsic scatter profile corrected for the covariance between M_gas and R₅₀₀ (see Sect. 5.1.4), which results in a suppression of the scatter by a factor of about two at R₅₀₀.