what is incidence

The term "incidence" refers to the number of new cases of a disease or health condition that occur in a specific population over a defined period of time. It is often expressed as a rate and is a measure of how commonly or frequently a disease occurs in a specified population. Incidence can be measured as a proportion or as a rate, and it is an important epidemiological measure for understanding the risk of a disease for a particular population. To calculate incidence, three elements must be defined: the number of new cases, the population at risk, and the time period