Illustration of the method in the stellar mass and SFR plane. Left panel: dashed red lines show the distribution of galaxies at an intermediate redshift. The solid red lines show the distribution of galaxies at slightly lower redshift. The colour in the background shows smoothed and continuous distribution of these points. We infer that when constructing an evolution criteria for galaxies (shown as arrows on right panel) that matches the change of distributions on the left panel, we can infer the evolution of galaxies.