2. SMALL-N DESIGNS u Experiments conducted on only one or a few subjects u External validity is a problem u Internal validity is often very good - no individual differences u Available population may be small

3. Reversal Designs u Measure before treatment, with treatment, and after treatment is removed or reversed (ABA Design) u The treatment is the independent variable u Measure the dependent variable at each stage of the design

4. Reversal Designs u Not appropriate for treatments with permanent effects u Variations: – ABAB – ABBA

5. Multiple Baseline Designs u Compare before and with treatment; use other behaviors, situations, or subjects as baselines u Useful when treatment has permanent effect

6. Multiple Baseline: Behaviors Behavior 1 before / Behavior 1 after Behavior 2 before ………. / Behavior 2 after Behavior 3 before ……………… TIME

7. Multiple Baseline: Situations Situation 1 before / Situation 1 after Situation 2 before ………. / Situation 2 after Situation 3 before ……………… TIME

8. Multiple Baseline: Subjects Subject 1 before / Subject 1 after Subject 2 before ………. / Subject 2 after Subject 3 before ……………… TIME

9. Statistics for Small-N Designs u Inferential statistics are not used u Use descriptive statistics; show data graphically