"The incidence is an epidemiological term for the number of new cases of a condition (e.g. brain tumours or diabetes), in a given population, during a specified time interval. The formulas for incidence can express it as a rate or a proportion, e.g. x new cases / y population count / z time period, or at given time, e.g. x new cases / y population count. Incidence should not be confused with prevalence."