VALIDITY AND RELIABILITY OF QUANTITATIVE ELECTROENCEPHALOGRAPHY (qEEG)

Reliability and validity are statistical concepts that are reviewed and then applied to the field of quantitative electroencephalography or qEEG. The review of the scientific literature demonstrated high levels of split-half and test re-test reliability of qEEG and convincing content and predictive validity as well as other forms of validity. qEEG is distinguished from nonquantitative EEG (“Eye Ball” examination of EEG traces) with the latter showing low reliability (e.g., 0.2 to 0.29) and poor inter-rater agreement for non-epilepsy evaluation. In contrast, qEEG is greater than 0.9 reliable with as little as 40 second epochs and remains stable with high test retest reliability over many days and weeks. Predictive validity of qEEG is established by significant and replicable correlations with clinical measures and accurate predictions of outcome and performance on neuropsychological tests. In contrast, non-qEEG or “Eye Ball” visual examination of the EEG traces in cases of non-epilepsy has essentially zero predictive validity. Content validity of qEEG is established by correlations with independent measures such as the MRI, PET and SPECT, the Glasgow Coma Score, neuropsychological tests, etc. where the scientific literature again demonstrates significant correlations between qEEG and independent measures known to be related to various clinical disorders. In contrast, non-qEEG or “Eye Ball” visual examination of the EEG traces in cases of non-epilepsy has essentially zero content validity. The ability to test and evaluate the concepts of reliability and validity are demonstrated by mathematical proof and simulation where one can demonstrate test re-test reliability for themselves as well as zero physiological validity of coherence and phase differences when using an average reference and Laplacian montage. Key Terms: Quantitative EEG, Reliability, Validity