Adaptive ABAB Design — Adaptive Reversal Design

The Adaptive ABAB Design is a single-subject experimental methodology that extends the classic ABAB reversal design by incorporating data-driven, prospective decision rules to determine when to transition between baseline (A) and intervention (B) phases. Rather than fixing phase lengths in advance, the researcher uses pre-specified criteria — such as stability thresholds, slope targets, or effect-size benchmarks — to guide each phase change, improving both experimental control and clinical responsiveness.