Standardised evolution of the hydrostatic mass bias, evaluated at several radii, 0.25R_vir, 0.5R_vir, 0.75R_vir and R_vir, for the sample of isolated major merger events. The time coordinate has been normalised to the virial timescale at the corresponding epoch as (t − t_merg)/τ_vir and is vertically aligned with respect to the panels to facilitate comparison. The colour bar illustrates the magnitude of the merger mass ratio, q, and the average mass bias trend is depicted in blue with the corresponding 1σ and 2σ shadowed areas.