P–P plot for the recovery of A_GWB from the SMHBH_set (orange) and createGWB_set (green). The solid lines are obtained from the log₁₀A_GWB posteriors of the MCMC runs over all 62 noise parameters of the pulsars array. The dashed lines are obtained by fixing all noise parameters in the recovery model; thus, A_GWB is the only free parameter. The dotted lines are also from posteriors obtained sampling only over A_GWB, but in a dataset where the realisations do not all have the same spectral amplitude. Here, the injected background has an amplitude value extracted from the prior distribution used in the recovery.