  The characterization of out-of-local-thermal-equilibrium plasmas requires the
use of collisional-radiative kinetic equations. This leads to the solution of
large linear systems, for which statistical treatments such as configuration
average may bring considerable simplification. In order to check the validity
of this procedure, a criterion based on the comparison between a partial-rate
systems and the Saha-Boltzmann solution is discussed in detail here. Several
forms of this criterion are discussed. The interest of these variants is that
they involve each type of relevant transition (collisional or radiative), which
allows one to check separately the influence of each of these processes on the
configuration-average validity. The method is illustrated by a
charge-distribution analysis in carbon and neon plasmas. Finally, it is
demonstrated that when the energy dispersion of every populated configuration
is smaller than the electron thermal energy, the proposed criterion is
fulfilled in each of its forms.
