Which statement best defines incidence rate?

Which statement best defines incidence rate?

• A. The total number of existing cases at a single point in time divided by the population.
• B. The number of new cases during a defined period divided by the population at risk, usually expressed per 1,000 or 10,000.
• C. The proportion of the population that has ever had the disease.
• D. The number of deaths among those with the disease divided by the total population.

Answer: (B)