Objectives

After reading Chapter 9, you should have mastered each of the following objectives.

1. Explain the purpose of experimental research designs and identify the two essential characteristics of all experimental research designs.
2. Define internal validity. Identify the threats to internal validity and give examples of each threat.
3. Define external validity. Identify five factors affecting external validity.
4. Describe three pre-experimental designs and identify the threats to internal validity (1, 2, 3) relevant to each design.
5. Describe two quasi-experimental designs and identify the threats to internal validity relevant to each design.
6. Describe four true experimental designs and identify the threats to internal validity relevant to each design.
7. Define the term factorial design. Explain the difference between main effects and interaction effects. Illustrate the purpose of factorial designs through an example of a two factor design.
8. Identify the criteria for evaluating experimental research designs and use this criteria to critique the design used in a published study.
9. Describe two single subject designs and identify the limitations of each.
10. Identify the criteria used to evaluate single subject research designs and use this criteria to critique the design used in a published study.