Histograms of the time-averaged 14–195 keV flux (top), of the variability index V from the χ² test (middle; the vertical dashed line indicates V = 1.3), and of the variability amplitude estimator S_V (bottom) for the total sample of 613 AGN (black) and for the selected sample of 110 AGN (red hatched). We assigned V = 10 to those objects with P_χ² < 10^-6. S_V could be computed for 464 of the BAT-detected AGN.