Enter the cumulative incidence rates of the exposed and non-exposed groups into the calculator to determine the risk difference.
- Cumulative Incidence Calculator
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- Absolute Risk Reduction Calculator
Risk Difference Formula
The following formula is used to calculate a risk difference.
Rd = CIe - CIn
- Where Rd is the risk difference
- CIe is the cumulative incidence of the exposed group
- CIn is the cumulative incidence of the non-exposed or control group
To calculate a risk difference subtract the cumulative incidence on the control group by the incidence of the exposed group.
Risk Difference Definition
A risk difference is a total difference between the incidence rates of a group of people exposed to disease when compared to those not exposed, usually considered the control group.
Risk Difference Example
How to calculate a risk difference?
- First, determine the cumulative incidence of the exposed group.
Using the calculator linked above, determine the CI of the exposed group.
- Next, determine the cumulative incidence of the control group.
Using the same method, determine the CI of the non-exposed group.
- Finally, calculate the risk difference.
Calculate the risk difference using the formula above.
A risk difference is a difference in the percentage of people that have a disease in an exposed group and a control group.