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Prevalence
Prevalence in epidemiology 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 seat-belt use). 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, 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 (e.g., 12 month prevalence), 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, toxicologists, 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.). The difference between prevalence and incidence can be summarized thus: prevalence answers “How many people have this disease right now?” or “How many people have had this disease during this time period?” and incidence answers “How many people per year newly acquire this disease?”
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Incidence (noun)
The act of something happening; occurrence.
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Incidence (noun)
The extent or the relative frequency of something happening.
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Incidence (noun)
The manner of falling; bearing or onus, as of a tax that falls unequally.
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Incidence (noun)
The striking of radiation or a projectile upon a surface.
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Incidence (noun)
A measure of the risk of a person developing a new condition within a specified period of time, usually a year.
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Incidence (noun)
The falling of a point on a line, or a line on a plane.
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Prevalence (noun)
The quality or condition of being prevalent; wide extension or spread.
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Prevalence (noun)
The total number of cases of a disease in a given statistical population at a given time, divided by the number of individuals in that population.
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Incidence (noun)
the occurrence, rate, or frequency of a disease, crime, or other undesirable thing
“an increased incidence of cancer”
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Incidence (noun)
the way in which the burden of a tax falls upon the population
“the entire incidence falls on the workers”
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Incidence (noun)
the intersection of a line, or something moving in a straight line, such as a beam of light, with a surface
“the point of incidence of the beam”