1. Complex Experimental Designs

2. Basic Experiment Simplest experimental design
Two levels of one independent variable
Compares only two groups

3. Increasing the Number of Independent Variables
Manipulate more than one IV
Typically, two or three IV’s are operating simultaneously
- Closer approximation of real-world conditions

4. Factorial Designs Factorial designs More than one IV (or factor)
All levels of each IV are combined with all levels of the other IV’s
Simplest factorial is a 2 X 2 factorial design

5. Berkowitz 2 X 3 Factorial Design Factor A (IV1): Mood State
Level 1 = Happy
Level 2 = Neutral
Level 3 = Sad
Factor B (IV2):
Self Awareness Level
Level 1 = Mirror
Level 2 = No Mirror
DV: Helping Behavior

6. Other Factorial Designs
3 X 4 Factorial Design
2 X 2 Factorial Design
2 X 2 X 2 Factorial Design
Identify the number of experimental conditions
in each of these designs.

7. Main Effects and Interactions
Interpretation of Factorial Designs
Two kinds of information
Main effect of an independent variable
Interaction between the independent variables

8. Main Effects and Interactions
A main effect tells us the effect each variable has by itself.
An interaction tells us that the effect of one independent variable depends on the particular level of the other.
Outcomes of a 2 X 2 factorial design
Interactions and simple main effects

9. IV x PV Designs
Factorial designs with manipulated and nonmanipulated variables (sometimes called IV x PV designs
Independent variable (IV) x participant variable (PV)
Allows researchers to examine how different individuals respond to the same manipulated IV

10. Between and Within Group Designs
Assignment procedures and factorial designs
Two basic ways of assigning participants to conditions
1. Between (Independent) groups design
2. Within (Repeated measures) design
Combination of the two basic ways is called a mixed factorial design