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 is a statistical measure used to assess the likelihood of an event occurring in one group compared to another. It is a ratio that compares the probability of an outcome happening in one group to the probability of the same outcome occurring in another group.

One key application of relative risk is in studying the effects of exposure to certain risk factors on the development of diseases. For example, researchers may investigate the relative risk of developing lung cancer in smokers compared to non-smokers. By calculating the relative risk, they can quantify the increased likelihood of developing lung cancer among smokers, providing valuable information for public health interventions and targeted prevention strategies.

Relative risk also plays a vital role in clinical trials and in evaluating the effectiveness of interventions or treatments. Researchers compare the relative risk of an event occurring in the treatment group to that in the control group. This analysis enables them to determine whether the intervention has a significant impact on reducing the risk of the outcome or disease.

## 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.