Fig. 1

Left: power curves when the individual Z-test (red lines) and WLS_s2 (blue lines) are used respectively for testing H₀₂, both using stage two control responses. Right: reduction in \(var(\hat {\delta }_{2})\) when stage one control responses is used relative to not using stage one control responses. Line types correspond to different values of n₂₂ when the new arm is added to the on-going trial. The timing of adding the new arm is reflected by n₀₁/n₀ on the x-axis