1. An apparatus comprising: at least one processor; a memory coupled to the at least one processor; a cohort analysis mechanism residing in the memory and executed by the at least one processor that answers a question by identifying cohorts for a person in the question, wherein the cohorts are persons meeting a threshold of similar attributes to the person of the question and available in a corpus of data; and wherein the cohort analysis mechanism aggregates data of the cohorts, extracts answers and evidence from data of the cohorts and combines and ranks the answers and evidence from data of the cohorts to answer the question.