After reading this chapter, you should be able to

• Explain the difference between strong experimental research designs and quasi-experimental research designs.
• Explain the limitations of quasi-experimental designs in making causal inferences compared to strong designs.
• Explain the characteristics of the nonequivalent comparison-group quasi-experimental design and how to search for rival hypotheses that might explain the obtained results.
• Explain the characteristics of the interrupted time-series designs.
• Explain how the regression-discontinuity design assesses the effect of a treatment.
• Explain how time-series and single-case research designs attempt to rule out confounding variables.
• Explain how a treatment effect is demonstrated in single-case research designs.
• Explain the limitations of each of the single-case research designs.
• Recognize and understand the methodological issues in single-case research designs.