characteristic of inheres in quality infection incidence proportion Lindsay Cowell Alexander Diehl A quality that inheres in an organism population and is the proportion of members of the population not infected at the beginning of a specified period of time who become infected during the specified period of time. Albert Goldfain An instance of infection incidence proportion is measured by dividing a measure of an instance of infection incidence by the number of members of the population not infected at the beginning of the specified period of time over which the incidence was measured. cumulative incidence of infection organism population