Any factor, trait, or condition that can exist in differing amounts or types. In an experiment, the experimenter changes one variable (the independent variable) and observes the resultant changes in one or more of the other variables (the dependent variables). The experimenter may, optionally, hold one or more variables constant (controlled variables) in order to observe the effect in one independent variable. By convention, the independent variable is plotted on the x-axis.

SYNONYM: Attribute. Field.