. "Incidence proportion (also known as cumulative incidence) is the number of new cases within a specified time period divided by the size of the population initially at risk. For example, if a population initially contains 1,000 non-diseased persons and 28 develop a condition over two years of observation, the incidence proportion is 28 cases per 1,000 persons per two years, i.e. 2.8% per two years." . "Incidence Proportion"@en . . . . . . . "https://en.wikipedia.org/wiki/Cumulative_incidence"^^ . "https://en.wikipedia.org/wiki/Incidence_(epidemiology)"^^ . .