Mastering Experimental Research: Techniques, Variables & Validity

1. Chapter 8 Experimental Research

2. Experiments • Appropriate Technique? • Confounding variables • A Short History of the Experiment • Experiments and Theory • Experimental and Survey Methods to Test and Apply Identity Theory 2

3. Figure 8.1: Random Assignment and Random Sampling 3

4. Figure 8.2: How to Randomly Assign 5

5. Random Assignment Within-participants Within-groups Between-groups Unbiased Matching versus Random Assignment 4

6. Experimental Design Logic • The Language of Experiments • Parts of the Experiment • Treatment • Dependent variables • Pretest • Posttest • Experimental group 6

7. Experimental Design Logic • Control group • Random assignment • Steps in Conducting an Experiment • Control in Experiments • Deception • Confederates • Cover story 7

8. Experimental Design Logic • Types of Design • Experimental design • Classical Experimental Design • Preexperimental Designs • One-Shot Case-Study Design • One-Group Pretest–Posttest Design • Static Group Comparison 8

9. Experimental Design Logic • Quasi-Experimental and Special Designs • Two-Group Posttest-Only Design • Interrupted Time Series • Equivalent Time Series • Solomon Four-Group Design • Factorial Designs • Design Notation 9

10. Table 8.1: A Comparison of the Classical Experimental Design 10

11. Table 8.2: Summary of Experiment Designs with Notation 12

12. Internal and External Validity • The Logic of Internal Validity • Threats to Internal Validity • Selection bias • History • Maturation • Testing • Instrumentation 13

13. Internal and External Validity • Mortality • Statistical regression • Diffusion of treatment • Compensatory Behavior • Experimenter Expectancy • Demand Characteristics • Placebo effect 14

14. Figure 8.4: Double-Blind Experiment 15

15. Internal and External Validity • External Validity • Population Generalization • Field Experiments 17

16. Figure 8.5: Three Types of External Validity Generalization 18

17. Practical Considerations • Planning and Pilot-Tests • Instructions to Participants • Postexperiment Interviews • Debrief • Experimental Results: Making Comparisons • A Word on Ethics 19

18. Figure 8.6: Comparisons of Results, Classical Experimental Design,and Weight-Loss Experiments 20