Issues in Randomization Outline

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Take Home• Permuted block randomization– Stratified by site– Appropriate to sample size– Choose block size(s) appropriate tosample size• Randomize smallest independentelement at last possible second• ITT (intent to treat) analysisOutlineWhat is Randomization?‣Randomized Study Design• What is a random sample?• Introductory Statistical Definitions• Stat SoftwareStudy Design Taxonomy• Randomized vs. Non-Randomized• Blinded/Masked or Not– Single-blind, Double blind, Unblinded• Treatment vs. Observational• Prospective vs. Retrospective• Longitudinal vs. Cross-sectional20
Ideal Study - Gold Standard• Randomized• Double blind / masked• Treatment• Prospective• Parallel groupsTypes of Randomized Studies• Parallel Group - classic• Sequential Trials – physical sciences• Group Sequential trials - classic• Cross-over – very useful if useable• Factorial Designs - independence• Adaptive Designs – gaining popularityThreats to RandomizationIntegrity• Improper masking or blinding– Bias will creep into data• Excluding subjects who withdraw fromtreatment– Can lead to bias• Drop-out/missing data– Without ITT: Breaks randomization– With ITT: Weakens treatment result– Long trials may need to have a screeningperiod to assess commitment of subjectsbefore randomization6321
Page 1 and 2: Issues in RandomizationLaura Lee Jo
Page 3 and 4: Random Sample vs.Randomization• R
Page 5 and 6: Should I Randomize?Almost Always YE
Page 7 and 8: Stratified Block Randomization Exam
Page 9 and 10: Eye-Opening Experiencefor Minimizat
Page 11 and 12: Example• Try this at home!- Or at
Page 13 and 14: Randomize 56, 3 TimesSimple Randomi
Page 15 and 16: Simple Block RandomizationRandomize
Page 17 and 18: Stratified Permuted BlockRandomizat
Page 19: Even if 2 weeks later?• Long term
Page 23 and 24: OutlineWhat is Randomization?Random
Page 25 and 26: OutlineWhat is Randomization?Random
Page 27 and 28: Studies: Early, Stages, Phases• E
Page 29 and 30: Phase III• A study to compare the
Page 31 and 32: Random Example (Game 2)• Everybod
Page 33 and 34: Other Software• STATA (Windows/Ma

Issues in Randomization Outline

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