Enter the cumulative incidence rates of the exposed and non-exposed groups into the calculator to determine the risk difference.

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?

1. First, determine the cumulative incidence of the exposed group.

Using the calculator linked above, determine the CI of the exposed group.

2. Next, determine the cumulative incidence of the control group.

Using the same method, determine the CI of the non-exposed group.

3. Finally, calculate the risk difference.

Calculate the risk difference using the formula above.

FAQ

What is a risk difference?

A risk difference is a difference in the percentage of people that have a disease in an exposed group and a control group.