  A new method is proposed for determining the critical indices of the
deconfinement transition in gauge theories, based on the finite-size scaling
analysis of simple lattice operators, such as the plaquette. A precise
determination of the critical index $\nu$, in agreement with the prediction of
the Svetitsky-Yaffe conjecture, is obtained for SU(3) gauge theory in
(2+1)-dimension. Preliminary results for SU(2) in (3+1)-dimension are also
given.
