t-Test on multiple columns Suppose you have a data set where you want to perform a t-Test on multiple columns with some grouping variable. As an example, say you a data frame where each column depicts the score on some test (1st, 2nd, 3rd assignment…). In each row is a different student. So you glance at the grading list (OMG!) of a teacher! How to do do that in R? Probably, the most “natural” solution would be some lapply() …