1. A method for determining a generalized spectral entropy of EEG signal data obtained from a patient, said method comprising the steps of: obtaining sequential EEG signal data from a plurality of electrodes applied to the patient; obtaining portions of the EEG signal data in which the signal is stationary in nature; determining an epoch length for the portions of the EEG signal so obtained; comparing the determined epoch length to a standard epoch length; for the portions of the EEG signal data so obtained, computing the spectral entropy of the EEG signal data; for the portions of the EEG signal data having an epoch length different from the standard epoch length, transforming the computed spectral entropy to that for an EEG signal portion having the standard epoch length; and displaying the computed spectral entropy of the EEG signal data, wherein the displayed computed spectral entropy is indicative of a depth of anesthesia for the patient.