  We introduce the mode area probability density function (MA-PDF) as a
powerful tool to study transverse Anderson localization (TAL), especially for
highly disordered optical fibers. The MA-PDF encompasses all the relevant
statistical information on TAL; it relies solely on the physics of the
disordered system and is independent of the shape of the external excitation.
We explore the scaling of MA-PDF with the transverse dimensions of the system
and show that it converges to a terminal form for structures considerably
smaller than those used in experiments, hence substantially reducing the
computational cost to study TAL.
