def _pairwise_chisq(self):
        """Pairwise comparisons (Chi-Square) along axis, as numpy.ndarray.

        Returns a list of square and symmetric matrices of test statistics for the null
        hypothesis that each vector along *axis* is equal to each other.
        """
        return [
            self._chi_squared(
                mr_subvar_proportions,
                self._margin[idx],
                self._opposite_axis_margin[idx]
                / np.sum(self._opposite_axis_margin[idx]),
            )
            for (idx, mr_subvar_proportions) in enumerate(self._proportions)
        ]