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