1. A method for answering a question in a question answering system, the method comprising the steps of: analyzing an input case representing the question to determine whether cohorts can be used with the input case, wherein the cohorts are similar entities with similar characteristics to an entity of the input case and available in a corpus of data; using cohort analysis to infer an attribute for the input case comprising: determining if the input case has an entity that has available cohorts; identifying cohorts in the corpus of data using fuzzy matching with a threshold percentage and where the cohorts are similar to the entity in the input case; analyzing the cohorts to find common attributes in the cohorts; finding missing attributes for the entity of the input case from the common attributes in the cohorts to infer a missing attribute for the input case; scoring the missing attributes according to consistency and sample size; applying confidence thresholds to the missing attributes to determine whether to infer the attribute for the refined input case; determining whether to dialog with a user to confirm the inferred attribute using a lower threshold compared to inferring the attribute without dialoging with the user; generating a refined input case that includes the inferred attribute applied to the entity of the input case; and using the refined input case with the inferred attribute to answer the question.