A processor-implemented method, computer program product, and/or computer system predicts a future event. A first bit array, which describes characteristics of a single entity while experiencing a first event, is generated using values received from a set of physical test devices. After the first single entity experiences a different second event, a second bit array is generated from another set of physical test devices. The second bit array describes characteristics of an event cohort, which is made up of entities, other than the single entity, which also experience the second event, but which never experienced the first event. When another single entity experiences the first event, a determination is made as to whether that other single entity has characteristics from both the first bit array and the second bit array. If so, a prediction is made that the other single entity will also experience the second event.