Inter-rater agreement for quantitative and raw EEG. In inter-rater agreement calculation, a portion of the observed percent agreement (PA), is assumed to be chance attributed (PC). The inter-rater agreement statistical methods are used to determine the percent agreement beyond chance (kappa). Fig. 3a. PA, PC, κ and CI for quantitative EEG spectrogram nomenclature are shown. Fig. 3b. PA, PC, κ and CI for raw EEG are shown. PA: Percent agreement; PC: Percent chance; CI: confidence interval; κ: kappa; κ 10–20% = slight agreement; κ 20–40% =fair agreement; κ 40–60%=moderate agreement; κ 60–80%=substantial agreement; κ 80–100%= near perfect agreement (Landis and Koch, 1977). GPD: generalized periodic discharge; GRDA: generalized rhythmic delta activity; LPD: lateralized periodic discharges; LRDA: lateralized rhythmic delta activity.