The incidence rate is a measure of the frequency with which a disease or other incident occurs over a specified time period. It is also known as the incidence density rate or person-time incidence rate, when the denominator is the combined person-time of the population at risk (the sum of the time duration of exposure across all persons exposed)
Applicable units are those of quantitykind:Incidence
https://en.wikipedia.org/wiki/Incidence_(epidemiology)
The incidence rate is a measure of the frequency with which a disease or other incident occurs over a specified time period. It is also known as the incidence density rate or person-time incidence rate, when the denominator is the combined person-time of the population at risk (the sum of the time duration of exposure across all persons exposed)