15. An apparatus, comprising: a processor; and a memory coupled to the processor, wherein the memory comprises instructions which, when executed by the processor, cause the processor to: receive an input question directed to a previous execution of a question answering (QA) system with regard to a previous input question; process the input question to generate at least one query for application to a corpus of information, wherein the corpus of information comprises information about the QA system and the previous execution of the QA system on the previous input question; apply the at least one query to the corpus of information to generate candidate answers to the input question; and output a final answer for the input question based on the candidate answers; wherein the input question is directed to identifying differences between the previous execution of the QA system and another previous execution of the QA system, and wherein the candidate answers identify possible sources of differences between the previous execution of the QA system and the another previous execution of the QA system.
15. An apparatus, comprising: a processor; and a memory coupled to the processor, wherein the memory comprises instructions which, when executed by the processor, cause the processor to: receive an input question directed to a previous execution of a question answering (QA) system with regard to a previous input question; process the input question to generate at least one query for application to a corpus of information, wherein the corpus of information comprises information about the QA system and the previous execution of the QA system on the previous input question; apply the at least one query to the corpus of information to generate candidate answers to the input question; and output a final answer for the input question based on the candidate answers; wherein the input question is directed to identifying differences between the previous execution of the QA system and another previous execution of the QA system, and wherein the candidate answers identify possible sources of differences between the previous execution of the QA system and the another previous execution of the QA system. 19. The apparatus of claim 15 , wherein the instructions further cause the processor to: identify a person associated with a change in the QA system corresponding to the final answer; and send a notification to the person to inform the person of results of the QA system obtained as a consequence of the change.