1. A method to identify relevant features in a deep question answering system, comprising: classifying a first case received by the deep question answering system; and while training the deep question answering system to answer the first case: identifying a first feature in the first case; computing a first feature score for the first feature by operation of one or more computer processors, wherein the first feature score indicates a relevance of the first feature in generating a correct response to the first case; and identifying the first feature as relevant in answering the classified first case upon determining that the first feature score exceeds a relevance threshold.