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.
See also:  Experimental Design and ANOVA