1) The variable that is managed or manipulated. In behaviour analysis, the independent variable often is a behavioural procedure, package, or other intervention or treatment program.

2) The variable the experimenter systematically manipulates to influence the dependent variable.

3) The environmental event or events whose presence or absence is manipulated by the researcher in order to determine its effects on the dependent variable.

"4) Any condition which is varied systematically in studying a change in the dependent variable (e.g., a stimulus, a reinforcing contingency, a schedule of deprivation, etc.

5) Any variable that is different from the dependent variable in that it can change independently of it. It is something that can change when the dependent variable does not or can remain the same when the dependent variable changes. An independent variable can also change in a different direction or at a different rate from the dependent variable. (For any dependent variable, there are thousands of independent variables. In looking for ""causes"" of behavior, we look for the particular independent variables of which behaviour is a function.)"