  Scaling properties of the quantum Hall metal-insulator transition are
severely affected by finite size effects in small systems. Surprisingly,
despite the narrow spatial range where probability structure functions exhibit
multifractal scaling, we clearly verify the existence of extended
self-similarity -- a hidden infrared scaling phenomenon related to the peculiar
form of the crossover at the onset of nonmultifractal behavior. As finite size
effects get stronger for structure functions with negative orders, the
parabolic approximation for the multifractal spectrum loses accuracy. However,
by means of an extended self-similarity analysis, an improved evaluation of the
multifractal exponents is attained for negative orders too, rendering them
consistent with previous results, which rely on computations performed for
considerably larger systems.
