Data Reduction

The purpose of quantitative techniques is to reduce the amount of data contained in a PSG to a far smaller, but manageable, number which at the same time provides information about particular aspects of the PSG. Sleep staging is an example of a quantitative data reduction technique; it is also relatively objective. Here we are focusing on data reduction techniques for EEG data that are both objective and quantitative.

I have sub-divided the methodology into frequency domain techniques, which quantify one or more features of the frequency composition of the data, and time domain techniques, which operate directly on the data. Sleep staging is thus a time domain technique for data reduction. Frequency domain techniques are based on the Fast Fourier Transform (FFT) of the data.