Statistical test of VEP waveform equality.

The aim of the study was to describe a theory and method for inferring the statistical significance of a visually evoked cortical potential (VEP) recording. The statistical evaluation is predicated on the pre-stimulus VEP as estimates of the cortical potentials expected when the stimulus does not produce an effect, a mathematical transform to convert the voltages into standard deviations from zero, and a time-series approach for estimating the variability of between-session VEPs under the null hypothesis. Empirical and Monte Carlo analyses address issues concerned with testability, statistical validity, clinical feasibility, as well as limitations of the proposed method. We conclude that visual electrophysiological recordings can be evaluated as a statistical study of n = 1 subject using time-series analysis when confounding effects are adequately controlled. The statistical test can be performed on either a single VEP or the difference between pairs of VEPs.