Calculate cumulative incidence (risk) of new cases in a population at risk per 100, 1,000 or 100,000 people with an exact Clopper–Pearson confidence interval.
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About this tool
Cumulative incidence (risk) with an exact confidence interval.
How to use Incidence Calculator
Enter the number of new cases during the period.
Enter the population at risk at the start.
Choose the multiplier and read the incidence with its interval.
Worked example
45 new cases among 3,000 people at risk is a cumulative incidence of 15 per 1,000 (95% CI 10.96 to 20.02).
What is the difference between incidence and prevalence?
Incidence counts new cases over a period; prevalence counts everyone who has the condition at a point in time.
Who is “at risk”?
People who could develop the condition during the period, so exclude those who already have it or cannot get it.
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