  We propose a generalization of multifractal analysis that is applicable to
the critical regime of the Anderson localization-delocalization transition. The
approach reveals that the behavior of the probability distribution of
wavefunction amplitudes is sufficient to characterize the transition. In
combination with finite-size scaling, this formalism permits the critical
parameters to be estimated without the need for conductance or other transport
measurements. Applying this method to high-precision data for wavefunction
statistics obtained by exact diagonalization of the three-dimensional Anderson
model, we estimate the critical exponent $\nu=1.58\pm 0.03$.
