Statistics Dictionary
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Extraneous Variable
Every experiment exists to examine a cause-and-effect relationship. With respect to the
relationship under investigation, an experimental design needs to account for three types of variables:
- Dependent variable. The dependent variable is the outcome being measured, the effect
in a cause-and-effect relationship.
- Independent variables. An independent variable is a variable that is explicitly
included in an experiment, because the experimenter believes it is a potential cause in a
cause-and-effect relationship.
- Extraneous variables. An extraneous variable is any other variable
that could affect the dependent variable, but is not explicitly included in the experiment.