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 equation:

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 calculates the risk in the exposed group, while the denominator calculates the risk in the unexposed group.

3. Interpretation of Relative Risk

Details:

• RR = 1: No association between exposure and outcome
• RR > 1: Increased risk in exposed group
• RR < 1: Decreased risk in exposed group (protective effect)

4. Using the Calculator

Tips: Enter all four values from your 2x2 table. All values must be non-negative integers. The calculator will compute the Relative Risk.

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 is Relative Risk most appropriate?
A: RR is ideal for cohort studies and randomized controlled trials where you can measure incidence.

Q3: What does an RR of 2.0 mean?
A: It means the exposed group has twice the risk of the outcome compared to the unexposed group.

Q4: How precise is Relative Risk?
A: RR should be reported with confidence intervals to understand its precision and statistical significance.

Q5: Can RR be negative?
A: No, RR ranges from 0 to infinity. Values between 0-1 indicate reduced risk, 1 indicates no effect, and >1 indicates increased risk.