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Survival Analysis Sample Size Calculator
Sample size and power for time-to-event endpoints using the log-rank test
Sample Size
Power
Statistical Power (1−β)
Alpha (Type I Error, α)
Effect Size Input
Hazard ratio
Median survivals
Test Type
Two-sided
One-sided
Hazard Ratio (Treatment / Control)
Median Survival, Treatment (months)
Median Survival, Control (months)
Allocation Ratio (n₂/n₁)
Accrual Period (months)
Follow-up Period (months)
Calculate Sample Size
Results
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Effect Size Input
Hazard ratio
Median survivals
Alpha (Type I Error, α)
Hazard Ratio (Treatment / Control)
Median Survival, Treatment (months)
n₁ (Control Group Size)
n₂ (Treatment Group Size)
Median Survival, Control (months)
Test Type
Two-sided
One-sided
Accrual Period (months)
Follow-up Period (months)
Calculate Power
Results
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