Glossary

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ecologic bias

The failure of inferences based on group-level (aggregated) analyses to reflect the effect at the individual level. (Adapted from: Rothman and Greenland 1998)


effect modification

Arises when the level of association between an exposure and an outcome varies by a third factor. (Adapted from: Centers for Disease Control and Prevention 2014)


environmental factor

An extrinsic factor (e.g., geology, climate, insects, sanitation, or health services) that affects an agent and the opportunity for exposure. (Adapted from: Centers for Disease Control and Prevention 2014)


epidemiology

The study of the distribution and determinants of health conditions or events among populations. (Adapted from: Centers for Disease Control and Prevention 2014)


exposed group

A group whose members have had contact with a suspected cause of, or possess a characteristic that is a suspected determinant of, a particular health problem. (Adapted from: Centers for Disease Control and Prevention 2014)


exposure

Having come into contact with a cause of, or possessing a characteristic that is a determinant of, a particular health problem. (Adapted from: Centers for Disease Control and Prevention 2014)


exposure misclassification

A type of information bias in which a study participant’s exposure status is erroneously assigned. (Adapted from: Rothman and Greenland 1998)