Filling-factor functions of largest clusters and voids, ℱ(D_t) = V_max/V₀, as functions of the threshold density, D_t. Left panels: luminosity-limited SDSS samples. Middle panels: particle-density limited (biased) L512 model samples. Right panels: HR4 model samples. Left panels from top to bottom are for luminosity limits of M_r − 5logh = −18.0,   − 19.0,   − 20, 0,   − 21.0; middle panels from top to bottom are for samples with particle-density limits of δ₀ = 2,  5,  10,  20; right panels from top to bottom are for halo- mass-limited samples HR4.11, HR4.12, HR4.123, and HR4.13. Functions for clusters are plotted with solid lines, and those for voids with dashed lines; colours mark different smoothing lengths.