Procedure of a cohort study for two arms/groups: One group is exposed, with a negative-impact risk factor (e.g., smoking, environmental exposure, etc.) or a preventive-impact factor (e.g., exercise, vaccination, diet, support, etc. ). The second group is non-exposed. Prospectively, the frequency with which participants in the two cohorts become ill or do not become ill (outcome) is determined. The risk of disease/non-disease is reported as an absolute frequency for both cohorts.