We conduct a numerical experiment on a regular system which typically describes molecular vibrational modes. We find that randomly missing levels do not affect spectral properties significantly, but the effect of levels missing systematically in quantum number space can distort the statistics considerably, yielding results apparently consistent with the Berry-Robnik prediction for mixed systems. This observation underscores the important point that misleading interpretation of data is possible, and is of particular relevance in an experimental context.

• Received 24 February 1992

DOI:https://doi.org/10.1103/PhysRevA.46.2649