Normalised excess variance versus log(L_{2−10   keV}) for the ULXs. The dotted-filled region indicates the area with BH mass of (2.5−30) × 10³   M_⊙ and accretion rates of ṁ_Edd = (0.01−0.8). Dashed lines indicate the case B model for AGN-like objects with a BH mass of (2.5−30) × 10³   M_⊙ (from left to right along each line), and for accretion rates of ṁ_Edd =  [0.01, 0.05, 0.1, 0.2, 0.5, 0.8] (from top to bottom).