The bootstrap test (Efron and Tibshirani, 1993) can apply to any metric; from prebootstrap test cision, recall, or F1 to the BLEU metric used in machine translation. The word bootstrapping refers to repeatedly drawing large numbers of smaller samples with bootstrapping replacement (called bootstrap samples) from an original larger sample. The intuition of the bootstrap test is that we can create many virtual test sets from an observed test set by repeatedly sampling from it. The method only makes the assumption that the sample is representative of the population.