Number of diseases in the experimental
Experimental Event Rate (EER)
Number of diseases in the control
Control Event Rate
RR of disease in EER and risk in CER
Risk Ratio
Difference in event rates for the EER and CER
Absolute Risk Reductin (ARR)
Relative to those who are in the control group
Relative Risk Reduction
No. of patient who would have to receive the treatment
Numbers Needed to Treat
Measure of Disease Occurrence
Average risk for developing a disease condition
More useful in determining etiologic/risk factors of disease
Incidence proportions
Measure of Disease Occurrence
Speed at which new cases occur
“Time at risk”
Incidence Rates