Plot of the Mg IIλ2796 EW versus M_*, SFR, and sSFR (from left to right). The empty blue circles are the results obtained here, the empty orange diamonds are the results of PR21 and the green empty squares are the results of RU14. The inset graph in each panel contains the probability distribution of the Spearman parameter from the bootstrap procedure in blue (see the text for more details) and the expected distribution in the uncorrelated case is shown in orange. The value of the mode of the obtained distribution and the significance in sigmas for the obtained correlation are also included. See the Sect. 4.1 for a discussion of correlation.