We first generate unanswerable questions using the trained generation model.
we use EM / F1 BERT Base 74.3/77.4 -+ TFIDF 75.0/77.8 +0.7/+0.4 + RULE 75.6/78.5 +1.3/+1.1 + SEQ2SEQ 75.5/78.2 +1.2/+0.8 + PAIR2SEQ 76.4/79.3 +2.1/+1.9 Table 5: Results using different generation methods for data augmentation. "