Incidence is the number of new cases of a condition, symptom, death, or injury that develop during a specific time period, such as a year.
Incidence shows the likelihood that a person in a certain population will be affected by that condition.
Stedman's Online Medical Dictionary. www.stedmansonline.com/content.aspx?id=mlrI1400001043&termtype=t. Accessed April 21, 2015.