Retrieved Y_SZ − M₅₀₀ scaling relation on 100 synthetic calibration samples compared with the true underlying relation used for sample generation. The retrieved slope (divided by three for better readability) is shown in blue, the retrieved intrinsic scatter in green, and the relevant combination of the degenerated parameters (1 − b) and Y* in red. The true value of each parameter is shown by the black dashed lines and the mean uncertainty returned by the calibration procedure is shown by the grey contours.