Fig. 2. Moment by moment TANCOVA results obtained when correlating 74 channel visual, German-language evoked ERP data with German proficiency scores. The data were obtained in an ongoing study investigating American students learning German. The significance (vertical, upper graph) and the correlation coefficient with its 95% studentized confidence interval (vertical, lower graph) are shown as function of time (horizontal axis). There was a significant effect of language proficiency between 400 and 500 ms and around 900 ms post-stimulus. Note that during periods of non-significance, the confidence interval of r often includes zero, which is closely related to the null hypothesis we tested, namely that there may be no relation. Regarding the width of the confidence interval, the simulations shown in Fig. 1 indicate that one may be able to reject the null-hypothesis while the estimation of the covariance map (and thus the correct r-value) might contain considerable noise and thus be quite uncertain.
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