  The localization behavior of the Anderson model with anisotropic hopping
integral t for weakly coupled planes and weakly coupled chains is investigated
both numerically with the transfer matrix method and analytically within the
self-consistent theory of localization. It is found that the mobility edge is
independent of the propagating direction. However, the correlation
(localization) length in the extended (localized) side of the transition can be
very different for the two directions. The critical disorder W$_c$ is found to
vary from t$^{1 \over 4}$ for weakly coupled planes to t$^{1 \over 2}$ for
weakly coupled chains.
