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 probability of the event occurring in the non-exposed group.

2. How Does the Calculator Work?

The calculator uses the Relative Risk formula:

Where:

• \( a \) — Number of exposed individuals with disease
• \( b \) — Number of exposed individuals without disease
• \( c \) — Number of unexposed individuals with disease
• \( d \) — Number of unexposed individuals without disease

Explanation: The numerator is the probability of disease in the exposed group, while the denominator is the probability of disease in the unexposed group.

3. Interpretation of Results

Details:

• RR = 1: No association between exposure and outcome
• RR > 1: Increased risk of outcome with exposure
• RR < 1: Decreased risk of outcome with exposure (potentially protective)

4. Using the Calculator

Tips: Enter the counts for each cell in the 2×2 contingency table. All values must be non-negative integers.

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: When should I use Relative Risk?
A: RR is most appropriate for cohort studies and randomized controlled trials where you can calculate incidence.

Q3: How precise should my RR value be?
A: Typically reported with 2 decimal places, but consider confidence intervals for statistical significance.

Q4: What are limitations of RR?
A: RR doesn't convey information about absolute risk and can be misleading when baseline risk is low.

Q5: Should I report confidence intervals with RR?
A: Yes, always report 95% confidence intervals to show the precision of your estimate.