  We study the level-statistics of a disordered system undergoing the Anderson
type metal-insulator transition. The disordered Hamiltonian is a sparse random
matrix in the site representation and the statistics is obtained by taking an
ensemble of such matrices. It is shown that the transition of levels due to
change of various parameters e.g. disorder, system size, hopping rate can be
mapped to the perturbation driven evolution of the eigenvalues of an ensemble
subjected to Wigner-Dyson type perturbation with an initial state given by a
Poisson ensemble; the mapping is then used to obtain desired
level-correlations.
