  We establish relations between the statistics of g factors and the
fluctuations of energy in metallic nanoparticles where spin-orbit coupling is
present. These relations assume that the electron dynamics in the grain is
chaotic. The expressions we provide connect the second moment of the g factor
to the root-mean square ``level velocity'' (the derivative of the energy with
respect to magnetic field) calculated at magnetic fields larger than a
characteristic correlation field. Our predictions relate readily observable
quantities and allow for a parameter-free comparison with experiments.
