Glossary

A glossary of general terms

$r^2$ (Coefficient of Determination)

The statistical measure $r^2$ calculates the fraction of the total signal variance that is accounted for by the task.

For small numbers of trials (<30 per label), determination coefficients can become rather large even if there is no significant effect. To assess significance under the (robust) assumption of Gaussianity, determination coefficients may be converted into t-values according to

$t^2=(n-2)frac{r}^{2}1-r^2$

and used in a one-tailed t-test against the "no correlation" null hypothesis.