  Recently an additional technique was applied to investigate the properties of
kHz QPOS, i.e. the analysis of the distribution of frequency ratios or
frequencies themselves. I review the results of such work on the data from
ScoX-1: Abramowicz et al. (2003), which was later criticized by Belloni et
al.(2005). I conclude that the findings of the latter paper are consistent with
results presented earlier: kHz QPOs cluster around the value corresponding to
the frequency ratio of 2/3. I also discuss the random walk model of kHz QPOs
and possible future observations needed to verify it.
