  We study various box-size scaling techniques to obtain the multifractal
properties, in terms of the singularity spectrum f(alpha), of the critical
eigenstates at the metal-insulator transition within the 3-D Anderson model of
localisation. The typical and ensemble averaged scaling laws of the generalised
inverse participation ratios are considered. In pursuit of a numerical
optimisation of the box-scaling technique we discuss different box-partitioning
schemes including cubic and non-cubic boxes, use of periodic boundary
conditions to enlarge the system and single and multiple origins for the
partitioning grid are also implemented. We show that the numerically most
reliable method is to divide a system of linear size L equally into cubic boxes
of size l for which L/l is an integer. This method is the least numerically
expensive while having a good reliability.
