Similar term(s): confounder, confounding variable.
A confounding factor in a study is a variable which is related to one or more of the variables defined in a study. A confounding factor may mask an actual association or falsely demonstrate an apparent association between the study variables where no real association between them exists. If confounding factors are not measured and considered, bias may result in the conclusion of the study.
Source: GreenFacts
Bias - Epidemiological studies
Español: Factores de confusión