Differential number counts at 850 μm in the data (green points), underlying source model of the quasar pair fields (blue), and 1σ spread of the differential number counts from 500 realizations of the source model (yellow shaded area). For comparison, we show the fiducial field model (black dashed) with its 1σ spread in 500 realizations (gray shaded area). We report the overdensity factor δ_cumul for each field in the panels.