Cumulative distribution of spurious sources (black histogram) and all detections (blue histogram) as a function of the S/N (1σ ~ 0.08 mJy), to estimate the spurious sources expected in the GLOSTAR survey. The red dashed line fitted to the negative detections indicates the expected spurious sources. Below 4.5 σ, the detections are dominated by spurious sources (occupying 93%) and the false detections decrease to 186 at 6.1 σ. Above 7 σ, fewer than 5 sources are expected to be false.