Single-Factor (IV) designs

1. Single-Factor (IV) designs • All these designs we’ve talked about so far have investigated the effects of ______ IV (_______) or multiple levels of the ______ IV • But, research questions and hypothesis often involve multiple IV’s, and various levels of each IV

2. Factorial Designs • ________________________ investigate the effects of multiple independent variables • These studies investigate Multiple _______ (IVs) and ________ (variations) of those IVs • e.g., Participants in a two-factor design are exposed to particular level of factor A __________________ with particular level of factor B Factor B Factor A

3. Factorial Designs • You can use more than 2 factors, and more than two levels, but your study can get _____________, • Expressed in terms of Factor 1 levels __Factor 2 levels, etc. • How many numbers = how many _________ • Value of number = how many ________ e.g., a 2 x 2 design has __ factors and __ levels of each e.g., a 2 x 2 X 4 design has __ factors, with the first __ factors having __ levels of the IV, the third having ___ levels of the IV

4. Factorial Designs • Allows you to investigate how multiple variables ______ • Functional relationship is demonstrated when you see the _____________________________. • Require many groups (2 x 2 = __ groups, 2 X 3 = __ groups) • Can detect 2 kinds of effects • _____________: a factor (IV), regardless of level of other factor (IV), produces an effect • ______________: a factor (IV) only produces an effect at one level of the other factor (IV)

5. Factorial Designs: Example Factor (IV): A. Context: Gain or Loss B. Outcome type: Hypothetical or Real Level (variations of IV) A1. Money gains A2. Money losses B1. Hypothetical money B2. Real money Variables influencing risk taking: Factor A = Context Factor B = Outcome Type

6. ____ main effect, ____ interaction A B

7. Main effect, no interaction ________________: A B Main effect Factor ____

8. Main effect, no interaction __________________: A B Main effect Factor ___

9. Main effect, no interaction ___________________: A B Main effect Factors ___________

10. No main effect, interaction effect A B Lines are not _______: Effects of one IV ________ on the the level of another IV

11. Main effect, interaction effect, but _____________ more important A B Two main effects but, lines are not ___________: Effects of one IV depends on the level of another IV

12. Factorial Design w/ Repeated measures • A factorial design in which you measure performance in subjects _____________ • Controls for _____________________ Example: Experimenter is interested in investigating the effects of a drug on performance rats given different diets. Each rat is given both diets and exposed to each drug dose.

13. Factorial Design w/ Repeated measures Diet Drug dose

14. Mixed design- between/within subject • A factorial design in which you measure performance in subjects _________________ • Have at least one __________-subjects factor and one ___________-subjects factor Example: Experimenter is interested in investigating the effects of a drug on performance rats given different diets. Each rat is given one diet type (between-subjects variable) and exposed to each drug dose (within-subject variable).

15. Mixed design- between/within subject Diet Drug dose Drug is the ______subject variable, Diet is the ______ subject variable

16. Subject Variable • In some research designs, quasi-experimental research, investigators try to relate _________ variables or non-manipulatable variables to behavior • Subject variable = __________ characteristic of individuals, e.g., gender, personality, presence of a disorder, age, IQ, • ___________ because it is not manipulated • You cannot attribute results to subject variable because other variables were ____________

17. Factorial Design w/ Quasi-Independent (Subject) variable (PXE) Quasi-independent or Subject variable – Variable that ____________ in the population and is not ______________, or ______. Example: Factor A. Outcome type Classification variable (non-manipulated): gender Gender Outcome Type

18. TEST your knowledge • A factor is another name for what? • A 2 X 3 X 2 factorial design has how many IV’s? How many levels of each IV • Draw the results of a factorial design study showing 1 main effect, an interaction.

19. Describe the design of this study: In a study of circadian variability in skin sensitivity, a researcher examines 2-point thresholds for 20 participants. Each is tested on three different areas of the body (thumb, forehead, thigh) at three different times of the day (9 AM, 3 PM, 9 PM, and 3 AM). The 2-point threshold is the distance between two points (in cm) touching the skin, at which a participant perceives them as two points instead of one. ______________________

20. In a study of crowding, introverts and extraverts are to be compared. Some are tested in a large room (8’ x 8’), others are tested in a medium-sized room (6’ x 6’) and others are tested in a small room (4’ x 4’). To see if expectations will influence the outcome, half the participants in each group are told that the study hypothesizes that crowding will harm their performance; the remaining participants are told nothing about hypothesis being studied. While in the room, participants fill out an anxiety survey (psychological test), then listen to a series of brief segments of five heavy metal songs and rank them from the most annoying to the least annoying _________________________________________