Part 1 Instructions: Answer the following questions using what you know about single-participant experimental research designs.

1.) Why is a single-participant design always a dependent-groups design?

2.) What three characteristics must a single-participant design have in order to be trusted?

3.) Provide your own example scenario for the following single-participant designs:

a.) ABA/ABAB Withdrawal

b.) Multiple-Baseline

c.) Alternating-Treatment

d.) Changing-Criterion

4.) How is validity evaluated in single-participant designs? Explain for each type of validity:

a.) Internal

b.) External

c.) Construct

d.) Statistical

Part 2 Instructions: For the following independent-groups scenarios you should:

• Identify whether the design is a posttest-only design or pretest-posttest design
• Identify the IV (or IVs; It may not be specified. In which case, you should assume the role of researcher and define the IV in a way that you think is appropriate)
• Identify the levels of the IV
  • If there is more than one IV, you should identify the different conditions (i.e., groups)
• Identify the DV
• Operationally define the DV (It may not be specified. In which case, you should assume the role of researcher and define the DV in a way you think is appropriate)
• State the Null Hypothesis
• State the Alternative Hypothesis (If there is evidence in the scenario that suggests the results will go a particular way, use this information to inform your Alternative Hypothesis)

1.) You want to know if vegans are healthier than meat-eaters. You assign 30 people to eat a vegan diet for one month. You assign another 30 to eat a meat-eater diet for one month. At the end of the month, you measure "health."

2.) Thinking about it, you realize a major confound in #1: it is impossible to know if diet caused vegans to be healthier, or if other lifestyle factors (like frequent exercise or smoking) were at play in one group but not the other prior to the manipulation. To remedy this, you find 60 meat-eater participants with equivalent lifestyles. Before they start the experiment, you measure their overall health and conclude that the 60 participants are not different from each other, health-wise. Then, 30 of the participants are required to eat a vegan diet for the next month, while the other 30 are to continue their normal diet. After one month, you measure "health" again.

3.) You want to know if a man's height influences whether people find him competent. You know from previous research that other physical attributes, like attractiveness, positively influence people's perceptions of a man's competence. To answer your research question, you create 90 videos of men at a job interview. 30 of these men are taller than average; 30 are average height; and 30 are shorter than average. Critically, you have controlled all other aspects of the interview videos such that the only appreciable difference is the interviewee's height. You have 120 participants watch the videos and evaluate "competence" on a 1-10 scale, where 1 means "not at all competent" and 10 means "extremely competent". 40 participants watch the "Tall" videos, 40 watch the "Average" videos, and 40 watch the "Short" videos.

*HINT: You will have more than one hypothesis

4.) Now you want to know whether height AND gender influence perceptions of confidence in interviews. You know from previous research that taller women are perceived as intimidating and assertive. You also know from previous research that women are often perceived as less competent than men in professional workplaces.¹ You conduct the same study as in #3 with the addition of gender. You have an equal number of male and female interview videos in each group. You have a new set of 120 participants watch the videos, split evenly among your conditions. Like last time, they rate the interviewee's competence on a scale of 1-10.

Part 3: Why are each of the designs in Part 2 Independent-Groups (Between-Subjects) designs?