From: Adaptive designs in critical care trials: a simulation study
Spending function | Function forms |
---|---|
O’Brien-Fleming (OBF) | \(\mathrm{\alpha }(\mathrm{t})=2-2\upphi (\frac{{\mathrm{Z}}_{1-\frac{\mathrm{\alpha }}{2}}}{\sqrt{\mathrm{t}}}) (\mathrm{t}\ne 0)\) |
\(\mathrm{\alpha }(\mathrm{t})= 0 (\mathrm{t }=0)\) | |
Hwang-Shih-DeCani (HSD) | \(\mathrm{\alpha }(\mathrm{t})=\mathrm{\alpha }(\frac{1-{\mathrm{e}}^{-\mathrm{\gamma t}}}{1-{\mathrm{e}}^{-\upgamma }}) (\upgamma \ne 0)\) |
\(\mathrm{\alpha }(\mathrm{t})=\mathrm{\alpha t }(\upgamma =0)\) |