Relative variance (diagonal terms) of the luminosity function covariance matrix at 0.2 ≤ z < 0.4 as a function of M_B for star-forming (top panel) and quiescent (bottom panel) galaxies. Red dots mark the shot noise contribution, and cyan pentagons the cosmic variance one. The grey areas in both panels show the magnitudes affected by the I₀ ≤ 24 selection, where V_eff/ ΔV < 1. The dotted vertical lines mark at z = 0.3 for reference.