2. Part Three SOURCES AND COLLECTION OF DATA
McGraw-Hill/Irwin
© 2003 The McGraw-Hill Companies, Inc.,All Rights Reserved.

3. Chapter Fourteen EXPERIMENTATION

4. Variables in Experiments
Independent variables
Dependent variables

5. Advantages of an Experiment?
Researcher’s ability to manipulate the independent variable
Contamination from extraneous variables can be controlled more efficiently
Convenience
Cost
Replication

6. Disadvantages of Experiments
Artificiality of the laboratory
Generalization from nonprobability samples
Larger budgets needed
Restricted to problems of the present or immediate future
Ethical limits to manipulation of people

7. Experimentation Process
Select relevant variables
Specify the treatment levels
Control the experimental environment
Choose the experimental design
Select and assign the participants
Pilot-test, revise, and test
Analyze the data

8. Ways to Assign Subjects
Random Assignment
Matching Assignment
Quota matrix

9. Does a Measure Accomplish What it Claims?
Internal validity
External validity

10. Threats to Internal Validity
History
Maturation
Testing
Instrumentation
Selection
Statistical Regression
Experimental Mortality

11. Threats to External Validity
The Reactivity of Testing on X
Interaction of Selection and X
Other Biasing Effects on X
Artificial setting of testing
Respondents knowledge of testing

12. Experimental Designs Preexperimental designs True experimental designs
Field experiments

13. X the introduction of an experimental stimulus to the participant
Design Symbols
X the introduction of an experimental stimulus to the participant
0 a measure or observation activity
R an indication that sample units have been randomly assigned

14. Preexperimental Designs
One-shot case study
One-group pretest-posttest design
Static group comparison

15. True Experimental Designs
Pretest-posttest control group design
Posttest-only control group design

16. Operational Extensions of True Designs
Completely randomized designs
Randomized block design
Latin square
Factorial design
Covariance analysis

17. Field Experiments: Quasi- or Semi-Experiments
Non Equivalent Control Group Design
Separate Sample Pretest-Posttest Design
Group Time Series Design