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Biostatistics & Research · single question

Which of the following best defines PREVALENCE in epidemiology?

  1. The proportion of individuals in a defined population who have a condition at a specific point in time (or over a defined period)
  2. The rate of new cases of a disease developing in a population during a specified time period
  3. The probability that a test will be positive when the disease is present
  4. The ratio of risk of disease in an exposed group versus an unexposed group
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Correct answer: A. The proportion of individuals in a defined population who have a condition at a specific point in time (or over a defined period)

Prevalence is an epidemiological measure that quantifies the proportion of a population that has a disease or condition at a specific time (point prevalence) or within a defined period (period prevalence). Prevalence = (Number of existing cases) / (Total population). In contrast, incidence measures only NEW cases occurring over a period. Prevalence is affected by both incidence and duration of disease (longer duration = higher prevalence). The original answer 'Autonomy' was completely unrelated to prevalence and appears to have been a data entry error. Autonomy is a dental ethics principle.

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