Relation between young stellar mass from CIGALE (M_young) and the observed Hβ luminosity for our sample of 2234 HII Galaxies with accurate SED fits (χ² < 3). The sample was divided into two groups according to their equivalent widths, EW(Hβ), corrected for contamination as described in Sect. 4.1. Objects in red have EW(Hβ) lower than the average of the sample (110 Å) while objects in blue have values above the average. The line shows a standard least-squares fit of slope very close to unity, as indicated in the legend. Typical error in M_young is < 30%.