After reading this chapter, you should be able to

• Explain how experiments produce evidence of causality.
• Describe the different ways an independent variable can be manipulated.
• Explain the importance of control in experimental research and how control is achieved.
• Explain the different ways of controlling the influence of potentially confounding variables.
• Explain why some experimental research designs are weak designs and others are strong designs.
• Compare and contrast factorial and repeated-measures designs.
• Explain the concept of an interaction effect.