Left: signal-to-noise ratio versus i band magnitude for the rWLQ sample (filled red squares; magenta frames: rWLQ-EWS subsample) and for the WLQ candidates that were rejected as noisy (black plus signs). For comparison, the contour curves show the distribution of the comparison sample (equally spaced logarithmic local point density contours estimated with a grid size of Δx,Δy = 0.1,0.05). Horizontal dashed line: explicit selection threshold S/N> 2, dotted line: 12th percentile of the rWLQ sample and 88th percentile of the unclassified noisy spectra at S/N = 9. Right: frequency distribution for the rWLQ sample (solid red), the rWLQ-EWS subsample (dashed magenta), and the WLQ candidates rejected as noisy (solid black). The histogram for the rWLQ-EWS subsample is stretched by a factor of two for better visibility.