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

- Cumulative Incidence Calculator
- Infection Rate Calculator
- Incidence Rate Calculator
- Prevalence Calculator
- 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.

## 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.