Also called a cause, predictor, or treatment variable (X). Represents an attribute (or element) of an object, idea, or event whose values are directly manipulated by the researcher. The independent variable is assumed to be the causal factor in a functional relationship with a dependent variable
Also called an effect, outcome, or criterion variable (Y). Represents an observable attribute or element that is the outcome of specified tests that is derived from manipulating the independent variable(s)
Variable the researcher controls so they do not affect the functional relationship between the independent and dependent variables included in the experiment.
Uncontrollable variables that should average out over a series of experiments. If not accounted for, they can have a confounding impact on the dependent variable measures that could weaken or invalidate the results of an experiment.