Question

which of the following best defines test variable (independent variable)?
the variable that is measured in an experiment.
the variable that stays the same in an experiment.
the variable that responds to the outcome variable.
the variable that is purposely changed in an experiment.

Explanation:

An independent variable (test variable) is the variable that is manipulated or changed by the experimenter. The first option describes the dependent variable (measured). The second option is a constant. The third option has an incorrect relationship (the dependent variable responds to the independent variable). The fourth option correctly defines the independent variable as the one purposely changed.

Answer:

The variable that is purposely changed in an experiment.