1. What is Risk Difference?

Risk Difference (RD) is an absolute measure of effect that represents the difference in risk between two groups. It is calculated as the risk in the exposed group minus the risk in the unexposed group.

2. How Does the Calculator Work?

The calculator uses the Risk Difference formula:

Where:

• \( P1 \) — Risk in exposed group (dimensionless)
• \( P2 \) — Risk in unexposed group (dimensionless)

Explanation: The risk difference provides a straightforward measure of the absolute effect size, showing how much the risk increases or decreases due to the exposure.

3. Importance of Risk Difference Calculation

Details: Risk difference is important in epidemiology and clinical research as it provides an absolute measure of risk change, which is often more clinically meaningful than relative measures for decision-making.

4. Using the Calculator

Tips: Enter risk values between 0 and 1 for both exposed and unexposed groups. The calculator will compute the difference between the two risks.

5. Frequently Asked Questions (FAQ)

Q1: What does a positive risk difference indicate?
A: A positive risk difference indicates that the exposure increases the risk of the outcome compared to the unexposed group.

Q2: What does a negative risk difference indicate?
A: A negative risk difference indicates that the exposure decreases the risk of the outcome, suggesting a protective effect.

Q3: How is risk difference different from relative risk?
A: Risk difference provides an absolute measure of effect size, while relative risk provides a ratio comparing the risk in exposed vs unexposed groups.

Q4: When should risk difference be used?
A: Risk difference is particularly useful when the absolute risk change is important for clinical or public health decision-making.

Q5: What are the limitations of risk difference?
A: Risk difference can be influenced by the baseline risk in the population and may not always provide the complete picture when comparing interventions across different populations.