The main signature of chaos in a quantum system is provided by spectral statistical analysis of the nearest neighbor spacing distribution and the spectral rigidity given by $Delta_3(L)$. It is shown that some standard unfolding procedures, like local unfolding and Gaussian broadening, lead to a spurious increase of the spectral rigidity that spoils the $Delta_3(L)$ relationship with the regular or chaotic motion of the system. This effect can also be misinterpreted as Berrys saturation.
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