Enter the total amount of people with a disease and without of two separate groups; one being the exposed group and one being the control. The calculator will determine the relative risk.

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## Relative Risk Formula

The following equation can be used to calculate the relative risk of two groups of people.

R = [ a / (a+b)] / [c/(c+d))]

- Where R is the relative risk
- a is the number of people in the exposed group with a disease
- b is the number of people in the exposed group without the disease
- c is the number of people in the control or base group with the disease
- d is the number of people ins the control group without the disease

## Relative Risk Definition

Relative risk measures the risk ratio of one group to another. In other words, it compares how many people get a particular disease when exposed to an outside factor with respect to a control group not exposed to that factor.

## Relative Risk Example

How to calculate the relative risk?

**First, determine the number of people with the disease in the exposed group**Measure variable a from the formula above.

**Next, determine the number of people without the disease in the exposed group.**Measure variable b from the formula above.

**Next, determine the number of people with the disease in the control group.**Measure variable c from the formula above.

**Next, determine the number of people without the disease in the control group.**Measure variable d from the formula above.

**Finally, calculate the relative risk.**Calculate the relative risk using the equation.

## FAQ

**What is relative risk?**

A relative risk is a ratio of the risk of contracting a disease based on exposure compared to a control group.