A depiction of<unk>  In epidemiology,<unk>  is the proportion of a particular population found to be affected by a medical condition (typically a disease or a risk factor such as smoking or seatbelt use) at a specific time. It is derived by comparing the number of people found to have the condition with the total number of people studied and is usually expressed as a fraction, a percentage, or the number of cases per 10,000 or 100,000 people.<unk>  is most often used in questionnaire studies.
Prevalence
Incidence 
Risk factor
Mortality rate
Infection rate
Case fatality rate
Risk of mortality
Threshold limit value