Central-tendency estimation and nearest-estimate classification of multi-channel evoked potentials.

By modeling evoked potentials (EPs) as random vectors in which the EP samples are random variables, a generalized strategy is introduced to determine multivariate central-tendency estimates such as the arithmetic mean, geometric mean, harmonic mean, median, tri-mean, and trimmed-mean. Additionally, a generalized strategy is introduced to develop minimum-distance classifiers based on central tendency estimates. Furthermore, procedures are developed to fuse the decisions of the nearest-estimate classifiers for multi-channel EP classification. The central-tendency estimates of real EPs are compared and it is shown that although the mathematical operations to compute the estimates are quite different, the EP estimates are similar with respect to their overall waveform shapes and latencies. It is also shown that by fusing the classifier decisions across multiple channels, the classification accuracy can be improved significantly when compared with the accuracies of individual channel classifiers.