Histogram of FWQM Hα to [O III] λ5007 Å line ratio for the star-forming, broad-line, and narrow-line AGNs in the training sample (blue, red, and green lines, respectively). We see that the distributions for the narrow-line AGNs and star-forming galaxies are almost identical, while the broad-line AGNs extend to a much larger FWQM ratio, with only a small fraction in the region of the star-forming galaxies or narrow-line AGNs. We also show the very-broad-line galaxies (QSO-like spectra) classified as AGNs (solid black line) and star-forming galaxies (dashed black line). We see that the majority of the QSO-like galaxies classified as star-forming galaxies have much larger FWQM ratios than bona fide star-forming galaxies, allowing us to use the FWQM ratio as a metric to correctly classify them.