Results in the (σ_a-v_a) and (-) planes for the whole sample simulated at z = 3. The panels and symbols are the same as those shown in Fig. 2. In all the panels we represent the following lines: red dashed lines represent the “optimal” frontiers, which give us the K_tot values for which the maximum index I is derived; the solid black line indicates the value derived according to Eq. (5), while the two dashed black lines represent the statistical frontiers ( MAD).