Luminosity segregation in the four group samples: galaxy luminosity fraction versus relative position of galaxy relative to the group centroid. The panels show the kernel density estimator contour level lines for CG₄, Control_4B, Control_4C, and RG₄ from top to bottom, respectively. The BGGs are shown in blue and the satellites in orange. The rank correlations and corresponding p values (in percent) are displayed for all galaxies of the group (i.e., including BGGs) and for the satellite galaxies (i.e., non-BGGs) only.