Scan of q-factors for different event sizes (x-axis) and BDT cuts (y-axis) using the 6 Hillas variables. For each size bin the color map shows the q-factors (normalized to 1) for different BDT cuts. The resulting optimal BDT cut (red) is shown together with the signal (green) and background (yellow) background efficiencies. The solid lines show the case for the size-dependent BDT cut while the dashed lines show the constant BDT cut.