In epidemiology, the prevalence or prevalence proportion is the proportion of a population found to have a condition (typically a disease or a risk factor such as smoking or seat-belt use). It is arrived at by comparing the number of people found to have the condition with the total number of people studied, and is expressed as a fraction, as a percentage or as the number of cases per 10,000 or 100,000 people. "Point prevalence" is the proportion of a population that has the condition at a specific point in time. "Period prevalence" is the proportion of a population that has the condition at some time during a given period ("12-month prevalence", etc), and includes people who already have the condition at the start of the study period as well as those who acquire it during that period. "Lifetime prevalence" (LTP) is the proportion of a population that at some point in their life (up to the time of assessment) have experienced the condition.

Prevalence estimates are used by epidemiologists, health care providers, government agencies and insurers. Prevalence is contrasted with incidence, which is a measure of new cases arising in a population over a given period (month, year, etc.).

Read more about Prevalence:  Examples and Utility, Limitations

Famous quotes containing the word prevalence:

    That the public can grow accustomed to any face is proved by the increasing prevalence of Keith’s ruined physiognomy on TV documentaries and chat shows, as familiar and homely a horror as Grandpa in The Munsters.
    Philip Norman, British author, journalist. The Life and Good Times of the Rolling Stones, introduction (1989)

    The prevalence of suicide, without doubt, is a test of height in civilization; it means that the population is winding up its nervous and intellectual system to the utmost point of tension and that sometimes it snaps.
    Havelock Ellis (1859–1939)