Preface. About the Author. 1. Introduction. 2. Drawing Valid Inferences I: Internal and External Validity. 3. Drawing Valid Inferences II: Construct and Statistical Conclusion Validity. 4. Sources of Artifact and Bias. 5. Selection of the Research Problem and Design. 6. Experimental Research: Group Designs. 7. Control and Comparison Groups. 8. Assessing the Impact of the Experimental Manipulation. 9. Observational Research: Case-Control and Cohort Designs. 10. The Case Study and Single-Case Research Designs. 11. Evaluation of the Single Case in Clinical Work. 12. Qualitative Research Methods: An Overview. 13. Assessment Methods and Strategies. 14. Assessment and Evaluation of Interventions. 15. Statistical Methods of Data Evaluation. 16. Interpretation of the Data. 17. Ethical Issues and Guidelines for Research. 18. Publication and Communication of Research Findings. 19. Closing Comments: Methodology in Perspective. Glossary. References. Author Index. Subject Index.