  In this Communication, we express our reservations on some aspects of the
interpretation of the Lempel-Ziv Complexity measure (LZ) by Mateo et al. in
"Interpretation of the Lempel-Ziv complexity measure in the context of
biomedical signal analysis," IEEE Trans. Biomed. Eng., vol. 53, no. 11, pp.
2282-2288, Nov. 2006. In particular, we comment on the dependence of the LZ
complexity measure on number of harmonics, frequency content and amplitude
modulation. We disagree with the following statements made by Mateo et al.
  1. "LZ is not sensitive to the number of harmonics in periodic signals."
  2. "LZ increases as the frequency of a sinusoid increases."
  3. "Amplitude modulation of a signal doesnot result in an increase in LZ."
  We show the dependence of LZ complexity measure on harmonics and amplitude
modulation by using a modified version of the synthetic signal that has been
used in the original paper. Also, the second statement is a generic statement
which is not entirely true. This is true only in the low frequency regime and
definitely not true in moderate and high frequency regimes.
