Which concept describes the number of new cases that occur within a given time frame, such as a year?

• A. Incidence
• B. Prevalence
• C. Comorbidity
• D. Equifinality

Answer: (A)

Incidence measures how many new cases appear in a population over a defined time period. It focuses on the rate at which the condition begins, which helps us understand the risk of developing it within that window. For example, if 150 new cases show up in a city of 10,000 people over one year, the incidence is 150 per 10,000 per year (about 1.5%). This is different from prevalence, which counts all existing cases (new and old) at a specific time. Comorbidity refers to having multiple disorders at once within individuals, not the rate of new cases in a population. Equifinality is a developmental idea describing multiple paths leading to the same outcome, not a measure of new occurrences. So the described concept is incidence.