The majority of the LMXBs are characterised by
aperiodic variability and the EXOSAT ME power spectra are dominated by a
continuum
``red noise'' component which gradually increases shortwards of 
Hz.
The presence of this continuum component affects the
statistical distribution of the power estimates in the spectrum.
This means that techniques that assign probabilities to power spectrum
peaks assuming the 
distribution of power expected from white noise
processes, overestimate
their significance. By using the already discussed technique (see
Chapter 3) a power spectrum for each source in the sample was performed and
analysed.