Topic: Why Multi-Arm Designs

Participant Counts in Separate Two-Arm Trials

Participant Counts With One Common Control

Equal Allocation Across Several Experimental Arms

Deriving the Shared-Control Sample-Size Saving

Diminishing Recruitment Savings as Arms Are Added

Choosing the Control-to-Treatment Allocation Ratio

A Checklist for Justifying a Shared Control

A Three-Treatment Comparison Under a Fixed Budget