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.

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?

  1. First, determine the number of people with the disease in the exposed group

    Measure variable a from the formula above.

  2. Next, determine the number of people without the disease in the exposed group.

    Measure variable b from the formula above.

  3. Next, determine the number of people with the disease in the control group.

    Measure variable c from the formula above.

  4. Next, determine the number of people without the disease in the control group.

    Measure variable d from the formula above.

  5. 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.

relative risk calculator
relative risk formula