Causal pie model

In the field of epidemiology, the causal mechanisms responsible for diseases can be understood using the causal pie model, where each pie in the diagram represent a theoretical causal mechanism for a given disease, which is also called a sufficient cause.[1] Each pie is made up many component factors, otherwise known as component causes. In this framework, each component cause represents an event or condition required for a given disease or outcome. A component cause that appears in every pie is called a necessary cause as the outcome cannot occur without it.[2]