  The return distributions of the coherent noise model are studied for the
system size independent case. It is shown that, in this case, these
distributions are in the shape of q-Gaussians, which are the standard
distributions obtained in nonextensive statistical mechanics. Moreover, an
exact relation connecting the exponent $\tau$ of avalanche size distribution
and the q value of appropriate q-Gaussian has been obtained as q=(tau+2)/tau.
Making use of this relation one can easily determine the q parameter values of
the appropriate q-Gaussians a priori from one of the well-known exponents of
the system. Since the coherent noise model has the advantage of producing
different tau values by varying a model parameter \sigma, clear numerical
evidences on the validity of the proposed relation have been achieved for
different cases. Finally, the effect of the system size has also been analysed
and an analytical expression has been proposed, which is corroborated by the
numerical results.

Statistical Mechanics