Causal relationship

When we look at causation we need to understand the difference between association and causation. To understand this it’s important to review and understand Rothman’s causal pie model. This model proposes that all of the pieces of the pie must be present to cause a disease. Each individual factor that contributes to the cause of a disease is shown as a piece of the causal pie. The pie is complete when all pieces are in place, meaning the disease occurs. Individual factors contributing to disease, called component causes, are deemed necessary or sufficient. They can be both necessary and sufficient or neither necessary nor sufficient.

Here is a link to the CDC with a great explanation of this model:

https://www.cdc.gov/csels/dsepd/ss1978/lesson1/section8.html

Necessary or sufficient:

A sufficient cause means every time it happens the outcome will follow. For example, the components that are necessary to cause AIDS are exposure to HIV, continued engagement in risky behavior with HIV positive individuals, and not taking the antiretroviral meds. All 3 components must occur for AIDS to develop but if one were absent then there would not be a sufficient cause for AIDS to occur.

A necessary cause means the outcome never happens without the cause but then sometimes the cause happens without the outcome. For example, in order to get influenza you must be exposed to the virus. We can also relate this to COVID, in order to get COVID you must be exposed to the virus, which is the necessary cause. If you are exposed to the virus you might not ever get COVID so exposure is a necessary condition but not a sufficient condition.

Discuss any other examples to give clarity to the causal pie components?

Use sources 5 years or less.

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