Issues in Randomization Outline

Response Adaptive• May be group sequential designs• May use continuous interimanalysis to feed into randomization• May use set interim i analysis timepoints to feed into randomization• Do not want response to be toolong termCluster Randomization• Same ideas as before• Unit of randomization– School/Clinic/Hospitals– Providers• Outcome measurement– Students– Patients• Need to use special models for analysisbecause those providing outcomesnested in unit that was randomizedWhat do I recommend?• Depends on the study andresources available• My go-to for researchers– Permuted block randomization– Stratified by site– Choose block size(s) appropriate tosample size– Randomize smallest independentelement at last possible second10