Group purity as a function of halo mass determined by abundance matching on luminosity for the FOF modified group catalogue (red) and Final Sample, combining FOF and halo-based methods (blue). Left panels: results for all sample, groups with four or more members and groups with ten or more (on top, middle and bottom panels, respectively). Right panel: group purity as a function of group multiplicity for the FOF modified group catalogue (red) and Final Sample (blue).