1. Experimental Design

2. Causal Effect
The finding that change in one variable leads to change in another variable, ceteris paribus (other things being equal)

3. Hypothesis?
Do individuals who view a violent videotape act more aggressively than individuals who view a nonviolent video tape?

4. Experimental Research
Population?
Assignment?
Dependent Variable?
Independent Variable?

5. Conditions Necessary for Determining Causality
Empirical Association
Appropriate Time Order
Nonspuriousness
Conditions Important in Specifying Causal Relationships
Mechanism
Context

6. Mean Noise Intensity by Type of Videotape

7. 2 X 2 Factorial Design
Violent Non-Violent
Predisposed X X
Yes
No X X

8. Violence on Television
Time Order
Violence on
Television
Commit
Violent Crime
Watch
Violence on Television
Violent Crime

9. Spurious Relationship
View the movie
Money Train
Commit violent crime
View the movie
Money Train
Feel enraged
against society
Commit violent crime

10. True Experiments Two comparison groups Random assignment
Assessment of change in the dependent variable

11. Classical Experimental Design
R O X O
O O

12. Quasi-Experimental Design Nonequivalent Control Group
Experimental: O1 X O2
Comparison: O1 O2
Experimental Pretest X Posttest
Comparison Pretest Posttest

13. Percentage of Drivers Using Seat Belts