We next analyzed question-summary pairs in terms of whether the summaries can be generated by an extractive method or an abstractive method is required.
we randomly selected pairs whose question text had 3-5 sentences and manually classified them into one of the following 3 categories: 1) The pair cannot be regarded as a question-summary pair, 2) An extractive method can generate a summary that is equivalent to the title, and 3) Others (i.e., an abstractive method might be needed to generate a summary that is equivalent to the title).