Incidence (epidemiology)
In epidemiology, incidence reflects the number of new cases of a given medical condition in a population within a specified period of time. == Incidence proportion == Incidence proportion (IP), also known as cumulative incidence, is defined as the probability that a particular event, such as occurrence of a particular disease, has occurred in a specified period: Incidence = number of subjects developing disease over a certain period total number of subjects followed over that period {\displaystyle {\text{Incidence}}={\frac {\text{number of subjects developing disease over a certain period}}{\text{total number of subjects followed over that period}}}} For example, if a population contains 1,000 persons and 28 develop a condition from the time the disease first occurred until two years later, the cumulative incidence is 28 cases per 1,000 persons, i.e.