The main signature of chaos in a quantum system is provided by spectral statistical analysis of the nearest-neighbor spacing distribution $P\left(s\right)\mathrm{}$ and the spectral rigidity given by the ${\Delta }_3\mathrm{}\left(L\right)\mathrm{}$ statistic. It is shown that some standard unfolding procedures, such as local unfolding and Gaussian broadening, lead to a spurious saturation of ${\Delta }_3\mathrm{}\left(L\right)\mathrm{}$ that spoils the relationship of this statistic with the regular or chaotic motion of the system. This effect can also be misinterpreted as Berry’s saturation.

• Received 27 July 2001

DOI:https://doi.org/10.1103/PhysRevE.66.036209