Flux distribution of [O III] and Hβ in our sample. The blue circles represent measurements with S/N_Hβ > 1.5, while the gray circles represent low-quality measurements with S/N_Hβ < 1.5. The blue dashed line marks the linear regression with the [O III]−Hβ relation, with the slope indicating the inverse of the median R3 ratio. Similar regression is applied to S/N_Hβ < 1.5 measurements, shown in the gray dashed line. No meaningful relations on R3 are constrained by those low-quality measurements.