  We study the three-dimensional Anderson model of localization with
anisotropic hopping, i.e., weakly coupled chains and weakly coupled planes. In
our extensive numerical study we identify and characterize the metal-insulator
transition by means of the transfer-matrix method. The values of the critical
disorder $W_c$ obtained are consistent with results of previous studies,
including multifractal analysis of the wave functions and energy level
statistics. $W_c$ decreases from its isotropic value with a power law as a
function of anisotropy. Using high accuracy data for large system sizes we
estimate the critical exponent as $\nu=1.62\pm0.07$. This is in agreement with
its value in the isotropic case and in other models of the orthogonal
universality class.
