Which research design uses baseline logic to demonstrate the effects of an intervention on the behavior of individual subjects?

• A. Withdrawal
• B. Reversal
• C. Single Subject Design
• D. Multiple Baseline

Answer: (C)

Baseline logic means you measure a person’s behavior before any intervention to establish a stable reference point, then compare that to behavior during the intervention. In a single-subject design, you repeatedly measure the same individual’s behavior across phases—baseline and treatment (and sometimes withdrawal or additional baselines). If the behavior changes when the intervention is applied and remains changed (or changes again when the intervention is withdrawn or modified), you have evidence that the intervention caused the change for that person. This approach centers on demonstrating a causal relation within one subject, which is what single-subject designs are built to do.