Left panel: original stratification of the magnetic field strength as a function of optical depth from the 3D MHD simulation B^mhd(τ_c) (solid-black line) for a particular point of the simulation domain (x = 500,y = 250; see Fig. 1). The color lines represent the results from the Milne-Eddington inversion of the Stokes profiles synthesized from the MHD simulation. Middle panel: here the solid-black is the same as on the left panel, B^mhd(τ_c); the dashed-black line represents the weighting function w_B(τ_c) employed to calculated the weighted average (dashed-dotted black line) according to Eq. (6). Right panel: comparison between the weighted average value of the magnetic field (dashed-dotted black line) from the numerical simulations with the magnetic field obtained from the M-E inversions (solid-color lines).