Reply to Chen et al.: Parametric methods for cluster inference perform worse for two-sided t-tests.
Eklund A., Knutsson H., Nichols TE.
One-sided t-tests are commonly used in the neuroimaging field, but two-sided tests should be the default unless a researcher has a strong reason for using a one-sided test. Here we extend our previous work on cluster false positive rates, which used one-sided tests, to two-sided tests. Briefly, we found that parametric methods perform worse for two-sided t-tests, and that nonparametric methods perform equally well for one-sided and two-sided tests.