Incidence rate

Our definition of Incidence Rate: 

The frequency or rate of something occurring in a given population. Incidence rate is most commonly stated and communicated in a percentage. Examples of incidence rates include:

• The percentage of people in the United States who own and drive a yellow car
• The percentage of people in California who own a computer
• The percentage of people in the France who are vegetarians

In market and opinion research, the incidence rate of a given population typically correlates to the level of effort needed to reach qualified or eligible research respondents.