Ratio of binned Planck data points to model for different model assumptions. The fiducial model (black diamonds) is shown together with results obtained by varying the underlying L₅₀₀ – M₅₀₀ relation from REXCESS to intrinsic (green plus signs), and by varying the slope of the underlying M₅₀₀ − Y_X relation from empirical to standard (red triangles). Thick bars give the statistical errors, while the thin bars are bootstrap uncertainties.