After 13 years there are new areas to discuss and more recent trials to be included. Good clinical practice; evaluation of quality of life; measurement of the benefit:risk comparison; determination of cost- effectiveness and cost utility; stopping rules for trials; meta-analysis and subgroup analysis are all new sections. The references are expanded from 305 to 512 and include the recent advances in trial design, such as the n-of-1 trials and megatrials, and up-to-date examples to illustrate the points made in the 20 chapters.After 13 years there are new areas to discuss and more recent trials to be included. Good clinical practice; evaluation of quality of life; measurement of the benefit:risk comparison; determination of cost- effectiveness and cost utility; stopping rules for trials; meta-analysis and subgroup analysis are all new sections. The references are expanded from 305 to 512 and include the recent advances in trial design, such as the n-of-1 trials and megatrials, and up-to-date examples to illustrate the points made in the 20 chapters.Preface. 1. Introduction. 2. The History of Controlled Trials. 3. Ethical Considerations. 4. The Objectives of a Randomised Controlled Trial. 5. Different Trial Designs. 6. How Many Subjects are Required for a Trial? 7. How to Ensure that the Results are Free of Bias. 8. Writing the Protocol. 9. Recruitment of Subjects. 10. Information to be Collected During a Trial. 11. The Conduct of the Trial - Good Clinical Practice. 12. Stopping Rules for Trials. 13. The Variability and Validity of Results. 14. Analysis of the Results, Subgroup and Meta-Analysis. 15. The Evaluation of Subjective Well-Being and Measurement of Quality of Life. 16. The Detection of Adverse Drug Reactions. 17. Measurement of the Benefit: Risk Comparison, Cost-Effectiveness and Cost-Utility. 18. Early Trials on New Drugs. 19. Failure to Accept the Results of Randomised Controlled Triall#˜