Rate
difference (RD) is the difference in incidence between the exposed and the non exposed.

**Attributable Rate (AR)**

Attributable
Rate (AR) is a measure of excess disease risk due to a particular exposure. It is determined as the proportion of cases in
the total population that is attributable to the exposure (risk factor). It is a measure of the impact of eliminating a particular
risk factor on disease risk.

There
are various mathematical formulations of AR that are beyond the scope of this session. They can be studied in advanced epidemiology
courses. The simplest formulation based on the odds or rate ratio is as follows

AR%= (RR-1) / RR *100.