Part 2: For each of the following topics, list the pros and cons of a between-subject and within-subject design and decide which would be better to use. Be sure you explain why and support your decision based on what you have read in the text:

• You want to test the relative effectiveness of two training programs for running a marathon.
• Using photographs of people as stimuli, you want to see if smiling people are perceived as more intelligent than people who are not smiling.
• You want to see if concrete nouns (e.g. dog) are recalled better than abstract nouns (e.g. truth).

Part 3: Imagine that an experiment shows that participants who receive psychodynamictherapy for dog phobia improve more than participants in a no-treatment control group. Explain a fundamental problem with this research design and at least two ways that it might be corrected.