Before revision:  We analyze two such datasets ( Natural Questions and TyDi QA ) to identify remaining headrooms : paragraph selection and answerability classification , i.e. determining whether the paired evidence document contains the answer to the query or not.
After revision:  We analyze two such datasets ( Natural Questions and TyDi QA . Our controlled experiments suggest two headrooms -- paragraph selection and answerability classification , i.e. determining whether the paired evidence document contains the answer to the query or not.