Home 
Contact 
Profile 
Videos 
Lecture by Professor Omar Hasan Kasule Sr. for Year 2 Semester 1 medical student PPSD session on 11th October 2006
Rate Difference (RD)
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% = (OR-1) / OR *100
- AR%= (RR-1) / RR *100.