Dust attenuation corrected EW_Hαversus the age of the young population in the starburst candidate sample. The sample is divided according to absolute magnitude into dwarfs and giants at M_r = −20. The solid and dashed lines are identical to those in the left part of Fig. 3 with a 3% relative mass fraction of the young population. The dotted line at EW_Hα = 150 Å corresponds to the minimum value (but not sufficient) of EW_Hα to qualify as a starburst with the b> 3 criterion and an age < 1 Gyr if the SFR is assumed to be constant during the burst. The hexagon symbols represent the surface density of the data points, where darker colours means more data.