1. What is Relative Risk?

Relative Risk (RR) is a measure of the strength of association between an exposure and an outcome. It compares the probability of an event occurring in the exposed group versus the unexposed group.

2. How Does the Calculator Work?

The calculator uses the Relative Risk formula:

Where:

• \( RR \) — Relative Risk (unitless)
• Incidence in exposed group — Probability of event in exposed group (unitless)
• Incidence in unexposed group — Probability of event in unexposed group (unitless)

Explanation: RR = 1 means no difference in risk between groups. RR > 1 means increased risk in exposed group. RR < 1 means decreased risk in exposed group.

3. Interpretation of Relative Risk

Details: Relative Risk is commonly used in cohort studies and randomized controlled trials to assess the effect of an exposure or treatment.

4. Using the Calculator

Tips: Enter incidence rates for both exposed and unexposed groups. Both values must be greater than 0.

5. Frequently Asked Questions (FAQ)

Q1: What's the difference between RR and OR?
A: Relative Risk compares probabilities directly, while Odds Ratio compares odds. RR is more intuitive but can't be used in case-control studies.

Q2: What is a significant RR value?
A: Typically RR > 2 or < 0.5 is considered strong, but statistical significance depends on confidence intervals.

Q3: When should I use RR?
A: Use RR when you can measure incidence directly, as in cohort studies or RCTs.

Q4: What are limitations of RR?
A: RR doesn't convey absolute risk differences and can be misleading when baseline risks are very low.

Q5: How do I calculate confidence intervals for RR?
A: CI calculation requires knowing the sample sizes in each group and typically uses a logarithmic transformation.