Readers not making a formal study of epidemiology will often see the names of epidemiological methods quoted without reference to their actual definition. Epidemiology is the scientific study of factors affecting the health and illness of individuals and populations, and serves as the foundation and logic of interventions made in the interest of public health and preventive medicine. ...

A number of basic concepts recur with particular frequency:

• Hazard ratio, also known as the Incidence Rate Ratio
• Odds ratio
• Risk ratio
• Relative risk, a generic term for Rate Ratio, Risk Ratio, and sometimes the Odds Ratio.

An online discussion forum of epidemiology methods and biostatistics is also available to post questions. The hazard ratio in survival analysis is a summary of the difference between two survival curves, representing the reduction in the risk of death on treatment compared to control, over the period of follow-up. ... The odds-ratio is a statistical measure, particularly important in Bayesian statistics and logistic regression. ... In statistics and mathematical epidemiology, relative risk (RR) of an event associated with the exposure is a ratio of probability of outcome of interest in exposed group versus treatment group. ...

Measures

1. Measures of occurrence
   1. Incidence measures
      1. Incidence density (also known as Incidence rate) (Szklo & Nieto, 2000)
      2. Hazard rate
      3. Cumulative incidence
   2. Prevalence measures
      1. Point prevalence
      2. Period prevalence
2. Measures of association
   1. Relative measures
      1. Risk ratio
      2. Rate ratio
      3. Odds ratio
      4. Hazard ratio
   2. Absolute measures
      1. Risk/rate/incidence difference
      2. Attributable risk
         1. Attributable risk in exposed
         2. Percent attributable risk
         3. Levin’s attributable risk
3. Other measures
   1. Virulence and Infectivity
   2. Mortality rate and Morbidity
   3. Case fatality
   4. Sensitivity (tests) and Specificity (tests)

The incidence of disease is defined as the number of new cases of disease occurring in a population during a defined time interval. ... The incidence of disease is defined as the number of new cases of disease occurring in a population during a defined time interval. ... Exponential failure density functions A failure rate is the average frequency with which something fails. ... Cumulative incidence is a measure of frequency, as in epidemiology, where it is a measure of disease frequency. ... In epidemiology, the prevalence of a disease in a statistical population is defined as the ratio of the number of cases of a disease present in a statistical population at a specified time and the number of individuals in the population at that specified time. ... Association may refer to: A voluntary association (also sometimes called an association) is a group of individuals who voluntarily enter into an agreement, explicit or implicit, to form or act as a body (or organization) to accomplish a purpose. ... The odds-ratio is a statistical measure, particularly important in Bayesian statistics and logistic regression. ... The hazard ratio in survival analysis is a summary of the difference between two survival curves, representing the reduction in the risk of death on treatment compared to control, over the period of follow-up. ... This article does not cite its references or sources. ... Virulence is either the relative pathogenicity or the relative ability to do damage to the host of an infectious agent. ... In Epidemiology, Infectivity refers to the ability of a ability of a pathogen to establish an infection. ... Mortality rate (the word mortality comes from mortal, which originates from Latin mors, death) is the number of deaths (from a disease or in general) per 1000 people and typically reported on an annual basis. ... In medicine, epidemiology and actuarial science, the term morbidity can refer to the state of being diseased (from Latin morbidus: sick, unhealthy), the degree or severity of a disease, the prevalence of a disease: the total number of cases in a particular population at a particular point in time, the... In epidemiology, Case fatality refers the rate of death among people who already have a condition. ... The sensitivity of a binary classification test or algorithm, such as a blood test to determine if a person has a certain disease, or an automated system to detect faulty products in a factory, is a parameter that expresses something about the tests performance. ... The specificity of a binary classification test with respect to a given class is the probability that the test correctly classifies case not belonging to that class. ...

See also

• Study design
• Epidemiology

A Study design is a way to set up an epidemiological investigation, as a form of clinical trial. ... Epidemiology is the scientific study of factors affecting the health and illness of individuals and populations, and serves as the foundation and logic of interventions made in the interest of public health and preventive medicine. ...

External links

• Epidemiologic.org Epidemiologic Inquiry online weblog for epidemiology researchers
• Epidemiology Forum A discussion and forum community for epi analysis support and fostering questions, debates, and collaborations in epidemiology
• The Centre for Evidence Based Medicine at Oxford maintains an on-line "Toolbox" of evidence based medicine methods.
• Epimonitor has a comprehensive list of links to associations, agencies, bulletins, etc.
• Epidemiology for the Uninitiated On line text, with easy explanations.
• North Carolina Center for Public Health Preparedness Training On line training classes for epidemiology and related topics.