A cohort analysis mechanism analyzes cohorts to infer one or more additional attributes for an input case to provide a refined input case to answer a question in a question answering system. The refined input case is then used to answer a question in the question answering system. The refined input case can be used in a traditional question answering flow or in a flow that again uses cohort analysis to extract relevant data to answer the question. The cohort analysis mechanism analyzes cohorts to find common attributes in the cohorts and then determines whether to infer the common attributes into the refined input case. The cohort analysis mechanism may determine to dialog with a user to confirm an inferred attribute.
Please help me write a proper abstract based on the patent claims. CLAIM: 1-8. (canceled) 9. 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 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, generating a refined input case that includes the inferred attribute; and using the refined input case with the inferred attribute to answer the question. 10. The method of claim 9 further comprising analyzing the cohorts to find common attributes in the cohorts and finds missing attributes in the case for the common attributes in the cohorts. 11. The method of claim 10 further comprising scoring the missing attributes. 12. The method of claim 11 further comprising applying confidence thresholds to the missing attributes to determine whether to infer the attribute for the refined input case. 13. The method of claim 12 further comprising determining whether to dialog with a user to confirm the inferred attribute. 14. The method of claim 13 wherein a lower threshold is used to determine whether to dialog with the user compared to inferring the attribute without dialoging with the user. 15. The method of claim 9 wherein the input case is a medical question for a patient and the cohort analysis mechanism processes the medical history of the patient and finds the cohorts from medical histories of other patients to predict an answer from the cohorts. 16. The method of claim 9 wherein the cohort analysis mechanism is part of a question answering application that answers a natural language question. 17. A method for utilizing cohorts in a question answering system, the method comprising: analyzing an input case in a question answering application that answers a natural language question to determine whether cohorts can be used with the input case, wherein the cohorts are 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: analyzing the cohorts to find common attributes in the cohorts and finds missing attributes in the case for the common attributes in the cohorts; scoring the missing attributes; applying confidence thresholds to the missing attributes to determine whether to infer the attribute for the refined input case; and determining whether to dialog with a user to confirm the inferred attribute; providing a refined input case that includes the inferred attribute; and answering a question with the refined input case. 18. The method of claim 17 wherein the input case is a medical question for a patient and the cohort analysis mechanism processes the medical history of the patient and finds the cohorts from medical histories of other patients to infer an attribute for the input case from the cohorts.