Attributable risk (AR)
Attributable risk (AR) is a measure of the proportion of disease that can be attributed to a particular exposure. In other words, it's a way of estimating how much of an illness is caused by a particular risk factor.
There are a few different ways to calculate AR, but they all rely on the same basic principle: you start by looking at the number of people who have the disease and then subtracting the number of people who don't have the disease but would have if it weren't for the exposure. This gives you the number of people who actually got sick because of the exposure. Then you divide that number by the total number of people who were exposed to see what percentage of cases were caused by the exposure.