1. What is Relative Risk Reduction?

Relative Risk Reduction (RRR) is a measure that shows how much the risk of an outcome is reduced in the experimental group compared to the control group. It's commonly used in clinical trials to demonstrate the effectiveness of treatments or interventions.

2. How Does the Calculator Work?

The calculator uses the RRR formula:

Where:

• \( CER \) — Control Event Rate (proportion of events in control group)
• \( EER \) — Experimental Event Rate (proportion of events in experimental group)

Explanation: RRR compares the risk difference (CER - EER) to the baseline risk (CER), showing the proportional reduction in risk between the two groups.

3. Importance of RRR Calculation

Details: RRR is important because it helps quantify treatment effects in relative terms, making it easier to compare the effectiveness of different interventions across studies with different baseline risks.

4. Using the Calculator

Tips: Enter CER and EER as proportions between 0 and 1 (e.g., for 25%, enter 0.25). Both values must be valid (CER > 0, EER ≥ 0).

5. Frequently Asked Questions (FAQ)

Q1: What's the difference between RRR and ARR?
A: RRR shows the proportional reduction in risk, while Absolute Risk Reduction (ARR) shows the simple difference in risk (CER - EER).

Q2: When is RRR most useful?
A: RRR is most useful when baseline risks vary, as it standardizes the treatment effect. However, ARR is better for understanding actual clinical impact.

Q3: Can RRR be negative?
A: Yes, a negative RRR indicates the experimental treatment increased risk compared to control.

Q4: What are limitations of RRR?
A: RRR can be misleading when baseline risk is low, as small absolute differences can appear large in relative terms.

Q5: How should RRR be presented?
A: RRR should always be presented with the baseline risk (CER) to provide proper context.