In single-subject research, which variable is the treatment provided and considered the cause?

• A. Independent Variables
• B. Dependent Variables
• C. Moderator Variables
• D. Control Variables

Answer: (A)

In single-subject research, the treatment you provide is the thing you actively manipulate to see if it produces a change in the target behavior. This is the independent variable because it is the factor you control and vary to observe its effect on the outcome, the dependent variable—the behavior or measurement you track. For example, introducing a prompting strategy aims to change the child’s number of correct responses; the prompting strategy is the independent variable, and the count of correct responses is the dependent variable. Moderator variables are factors that can influence how strong or in what direction that relationship appears, such as motivation or session context. Control variables are kept constant to prevent them from confounding the results. By repeatedly measuring the behavior across baseline and treatment phases, single-subject designs build a case that the treatment caused the observed change within the individual.