Printable Handouts

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Navigable Slide Index

1. Introduction
2. Background
3. Selection bias
4. Randomisation (1)
5. Quasi-alternation
6. True alternation
7. Alternation and selection
8. Randomisation (2)
9. Subversion
10. Foreknowledge of allocation
11. Subversion - evidence
12. Quantitative evidence
13. Poor concealment
14. Comparison of concealment
15. Allocation concealment and sequence generation
16. Concealment
17. More evidence
18. Case study (1)
19. Case study (2)
20. Mean ages of groups
21. More examples
22. Recent blocked trial
23. What is wrong here?
24. Problem?
25. Concealment: recommendations
26. Simple or restricted randomisation?
27. Restricted allocation
28. Blocking
29. What is current practice?
30. Restricted allocation and subversion
31. Possible subversion
32. Wither restricted allocation?
33. Testing for subversion
34. Prediction and cluster randomised controlled trials
35. Cluster trials
36. Consent bias
37. Hip protector trial
38. Review of cluster trials
39. Review results
40. Misleading trial
41. Baseline characteristics
42. Selection bias in recruitment
43. What happened?
44. UK BEAM trial
45. UK BEAM selection bias
46. UK BEAM participant recruitment
47. UK BEAM
48. Avoiding selection bias in cluster trials
49. Selection bias in meta-analysis
50. Selection bias in trials: summary

Topics Covered

• Introduction to selection bias
• Allocation methods
• Evidence for subversion bias
• Restricted or simple randomization
• Problems with cluster randomization
• Evidence for selection bias in cluster trials

Links

Series:

• Design and Analysis of Randomized Clinical Trials

Categories:

• Methods
• Pharmaceutical Sciences

Talk Citation

Torgerson, D. (2007, October 1). Allocation concealment, prediction and selection bias [Video file]. In The Biomedical & Life Sciences Collection, Henry Stewart Talks. Retrieved April 15, 2025, from https://doi.org/10.69645/YEWG9259.
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Publication History

• Published on October 1, 2007
• Archived on May 31, 2018

Financial Disclosures

• Prof. David Torgerson has not informed HSTalks of any commercial/financial relationship that it is appropriate to disclose.