Enter the control event rate and the experimental event rate into the calculator to determine the absolute risk reduction.

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## Absolute Risk Reduction Formula

The following equation is used to calculate an absolute risk reduction.

ARR = CER – EER

- Where ARR is the absolute risk reduction (%)
- CER is the control event rate (%)
- EER is the experimental event rate (%)

## Absolute Risk Reduction Definition

An absolute risk reduction is defined as the difference between the percentage rate of a control event and an experimental rate.

## Absolute Risk Reduction Example

How to calculate absolute risk reduction?

**First, determine the control rate.**Calculate the percentage rate of the control event rate.

**Next, determine the experimental event rate.**Calculate the experimental event rate.

**Finally, calculate the absolute risk reduction.**Calculate the absolute risk reduction using the formula above.

## FAQ

**What is an absolute risk reduction?**

An absolute risk reduction, or ARR for short, is a measure of the absolute difference between a control group and a group receiving a treatment to prevent the event from happening.

**What is an absolute risk?**

Absolute risk is a ratio of the number of people that have a particular event, typically a medical event, compared to the total number of people that it could happen to.