WHEATON Kristan

Analysis of Competing Hypotheses (ACH) is an intelligence analysis method based on evaluating plausible and exclusive hypotheses for a given question. It involves validating or invalidating hypotheses using available information; i.e., observed facts or existing data that essentially represent evidence for or against each hypothesis. Through a logical elimination process, ACH seeks primarily to refute rather than validate hypotheses. In short, it helps select those hypotheses compatible with the available information and retrieve the best possible estimate. ACH resembles Differential Diagnosis (DD) in medicine, whereby a particular disease is distinguished from others presenting some similar clinical symptoms in a patient. ACH enables the user to reduce cognitive bias, notably confirmation bias which compels people to seek evidence confirming their own prejudices. A later version of ACH, aptly named Structured Analysis of Competing Hypotheses (SACH), entails breaking down one complex question into simple questions then conducting a traditional ACH on each of these questions.