Ratios between X-ray and WL masses as a function of WL mass. Panel A) shows log (M^hyd/M^wl) within , panel B) shows log (M^Y/M^wl) within . WL masses assume the B13 c–M relation. We show three tests for a mass bias: the overall average logarithmic bias b = ⟨ log M^X − log M^wl ⟩ is denoted by a long-dashed line, and its standard error by a dark grey shading. Short-dashed lines and light grey shading denote the same quantity, but obtained from averaging over Monte Carlo realisations including the jackknife test. We also show this b_MC for the low-M^wl and high-M^wl clusters separately, with the 1σ uncertainties presented as boxes, for sake of clarity. As a visual aid, a dot-dashed line depicts the Monte Carlo/jackknife best-fit of log (M^X/M^wl) as a function of M^wl. In addition, panel A) also contains this best-fit line (triple-dot-dashed) for the case without correction for cluster member dilution; the corresponding data points follow the Fig. 1 scheme. Indicated by uncertainty bars, panel B) also presents three high-z clusters from High et al. (2012).