Compares how often an event happens per unit time between two groups.
The incidence rate ratio compares the rate of new events (e.g., injuries per 1000 training hours) between two groups, accounting for differing exposure times rather than just event counts. An IRR of 1.5 means one group has a 50% higher event rate than the comparator; it is typically reported with a confidence interval, and values spanning 1 indicate no clear difference. It is commonly used in cohort studies and injury surveillance where athletes accrue unequal exposure time.
This guide was auto-drafted and is pending editorial review.