Probability distribution of false detections, ${\mathcal{P}}_{\mathrm{F}\mathrm{D}}(x)$ noted as N_pos jacked, and the peak value distribution of the observations, ${\mathcal{P}}_{\mathrm{D}}(x)$ noted as N_pos real. Both distributions are obtained by running FindClump on the jackknifed cubes and the real data cube, respectively. From left to right, we show the three data sets of GLASS-z12, GLASS-z10, and S5-z17–1 (see Table 1). An excess of ${\mathcal{P}}_{\mathrm{D}}(x)$ over ${\mathcal{P}}_{\mathrm{F}\mathrm{D}}(x)$ is indicative of line detection. However, no such excess is detected.