The qEEG represents the statistical manipulation of the raw EEG, so an understanding of these manipulations should precede any discussion of the qEEGs clinical indications for protocols. Without such knowledge any given finding may be misinterpreted.
Following the careful recording of the EEG, the quantitative analysis is begun with the sampling of the data to be used in the analysis by the Fourier transform. The Fourier analysis assumes there are no transients (epileptic discharges, episodic voltage changes etc.) or state changes (light sleep, drug effect, mental task, etc.), so these must be avoided when selecting data for analysis in qEEG for eyes closed resting database comparison. There are some eyes open and task databases available more recently (Hudspeth, Sterman, Duffy etc.)