After reading this chapter, you should be able to:

1. Identify three categories of research design: experimental, quasi-experimental, and nonexperimental.
2. Explain how a gradient of control can be used to understand research design.
3. Define and explain internal and external validity.
4. Describe three elements of control required in an experiment.
5. Describe factors that threaten the internal validity of a research study.
6. Describe factors that threaten the external validity of a research study.
7. Define and explain mundane and experimental realism.