1. Establishing the Direction of the Relationship
The Experiment
Establishing the Direction of the Relationship

2. Research Strategies Non-Experimental Research Experimental Research
Descriptive Research (survey, archival, observational)
Correlation Research
Experimental Research
Between-Subjects Designs
Within-Subjects Designs
Factorial Designs
Quasi-Experimental Designs

3. Experimental Strategy
Establishes the existence of a cause-and-effect relationship between two variables.
The change in one variable causes a change in another variable.
X  Y

4. Comparison The essence of experimentation is looking for differences
GROUP A
GROUP B

5. Elements of an Experiment
Independent Variable
Random Assignment
Dependent Variable
Control

6. 1. Independent Variable
A condition or event that an experimenter varies in order to see its impact on another variable

7. Establishes Direction

8. Independent Variable Experimental (or Treatment) Group:
Participants who receive some special treatment
Control Group:
Participants who do not receive the special treatment

9. Elements of an Experiment
Independent Variable
Random Assignment
Dependent Variable
Control

10. 2. Random Assignment
Participants have an equal chance of being in any condition in the experiment

11. Elements of an Experiment
Independent Variable
Random Assignment
Dependent Variable
Control

12. 3. Dependent Variable
The variable that is thought to be affected by manipulation of the independent variable

13. 4. Control Extraneous Variable
Any variable other than IV that might influence the DV
Confounding Variable
When two variables are linked together in a way that makes it difficult to sort out their specific effects

14. Extraneous to Confounding
When it influences DV
Systematic Variation

15. Extraneous to Confounding
Coke
Dislike
Label L
Is the difference due to
the soft drink or the label
that is attached to the
soft drink?
PEPSI
Like
Label S

16. Elements of an Experiment
Independent Variable
Random Assignment
Dependent Variable
Control

17. Evaluating the Experiment
Advantages
Causal Statements
Disadvantages
Artificial
Ethical & Practical Limitations on manipulations