Incidence

The world is ever changing and so it's necessary to measure the frequency and duration of events. Measuring the development of disease is one such measurement and this measure is called incidence.

Measuring the situation at one time gives you prevalence. The number of cases is the numerator and the population at risk including cases is the denominator.

To measure incidence we measure the appearance of cases in a known population as time passes. The denominator is almost always expressed as a multiple of ten.

Incidence can be expressed as the incidence risk (sometimes called cumulative risk.) Or as incidence rate (sometimes called incidence density)