2. Single-Case Design
• Single-participant/subject/case
–Case study may or may not have baseline
• Stable-baseline Design
–Baseline control period prior to manipulation
–How do we know the manipulation is
responsible for observed difference(s) in DV?
3. ABA Design
• Reversal or withdrawal design
–Baseline (A) Treatment (B) Baseline (A)
• Question of internal validity
–History, maturation, testing, instrument
decay, & regression toward the mean
4. ABAB Design
• Single-subject baselines taken at multiple
intervals (yet not multiple-baseline design)
–Baseline (A) Treatment (B) Baseline (A)
Treatment (B)
• Question of internal validity
–History, maturation, testing, instrument
decay, & regression toward the mean
5. Multiple-Baseline Design
• Multiple-subject baselines
–Introduce intervention at different time
points for each participant
–Question of internal validity
–History, maturation, testing, instrument
decay, & regression toward the mean
6. Quasi-Experimental Designs
• Used when control features of
experimental designs cannot be achieved
–IV cannot be manipulated
–Cannot randomly assign participants to
conditions or orders of conditions
• Question of internal validity
–History, maturation, testing, instrument
decay, & regression toward the mean
