AN ALTERNATIVE METHOD FOR SIGNIFICANCE TESTING OF WAVE-FORM DIFFERENCE POTENTIALS

Guthrie and Buchwald (1991) proposed an ad hoc procedure for assessing the statistical significance of waveform difference potentials that m ay arise in a variety of psychophysiology research contexts. In our pa per, an alternative method is presented and demonstrated that has fewe r underlying assumptions than does the Guthrie-Buchwald test and may, therefore, produce better results in some situations. In particular, t he test proposed here (a) is distribution free, (b) requires no assump tion of an underlying correlation structure (e.g., first-order autoreg ressive), (c) requires no estimate of the population autocorrelation c oefficient, (d) is exact, (e) produces p values for any number of subj ects and time points, and (f) is highly intuitive as well as theoretic ally justifiable. This procedure may be used to carry out multiple com parisons with exact specification of experimentwise error, however, th is test is based on permutation principles and may require large amoun ts of computer time for its implementation.