Figure 2: Schematic of the multifractal spectrum at the Anderson transition. The typical spectrum is restricted to the region of positive $\mathit{\text{f}}(\alpha )$ and thus terminates at ${\alpha }_{-}$ and ${\alpha }_{+}$. In contrast, the average spectrum continues to negative $\mathit{\text{f}}(\alpha )$. The tails with negative $\mathit{\text{f}}(\alpha )$ (shaded region) are produced by rare events that do not occur in a typical wave function.