Relative Risk Calculator
Calculate the relative risk ratio between two groups to measure the strength of association between exposure and outcome.
Calculate Relative Risk
Table of Contents
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 outcome occurring in an exposed group to the probability of the same outcome occurring in a control group.
- Measures the strength of association
- Compares exposed vs. control groups
- Used in epidemiological studies
- Helps assess risk factors
Interpreting Relative Risk
RR > 1
Indicates increased risk in the exposed group compared to the control group.
RR = 1
Indicates no difference in risk between the exposed and control groups.
RR < 1
Indicates decreased risk in the exposed group compared to the control group.
Confidence Intervals
Help determine if the association is statistically significant.
Relative Risk Formula
The relative risk is calculated using the following formula:
Where:
- a = exposed with outcome
- b = exposed without outcome
- c = control with outcome
- d = control without outcome
Examples
Example 1 Increased Risk
Exposed Group: 40 with outcome, 60 without
Control Group: 20 with outcome, 80 without
RR = 2.0
The exposed group has twice the risk of the outcome
Example 2 No Association
Exposed Group: 30 with outcome, 70 without
Control Group: 30 with outcome, 70 without
RR = 1.0
No difference in risk between groups
Example 3 Protective Effect
Exposed Group: 20 with outcome, 80 without
Control Group: 40 with outcome, 60 without
RR = 0.5
The exposed group has half the risk of the outcome