WikiSuggest

To collect WikiSuggest, Google Suggest API is used to harvest natural language questions and submit them to Google Search. Whenever Google Search returns a box with a short answer from Wikipedia, an example from the question, answer, and the Wikipedia document are created. If the answer string is missing from the document this often implies a spurious question-answer pair, such as (‘what time is half time in rugby’, ‘80 minutes, 40 minutes’). Question-answer pairs without the exact answer string are pruned. Fifty examples after filtering are examined and 54% were found to be well-formed question-answer pairs where answers in the document can be grounded, 20% contained answers without textual evidence in the document (the answer string exists in an irreleveant context), and 26% contain incorrect QA pairs.

Source: Coarse-to-Fine Question Answering for Long Documents