Left panel: fraction of unconfirmed sources with respect to the total number of elements of the PSZ1-North sample (Dec ≥ −15°) as a function of the 857 GHz signal in MJy sr⁻¹ taking into account the entire sample (red squares), the S/N <  5.1 subsample (dark blue line), and the S/N ≥ 5.1 subsample (light blue line). Right panel: percentage of unconfirmed sources with respect the total number of elements of the PSZ1-North sample as a function of the galactic latitude. The error bars represents the Poisson uncertainty of the total number of sources in each bin.