Survival Analysis Sample Size

50%
80%

Results will appear here

Enter the expected hazard ratio and study parameters to calculate the required sample size for survival analysis.

Formula

Sample Size for Survival Analysis

Number of events required (Schoenfeld):

d=4(Zα/2+Zβ)2(ln⁡HR)2d = \frac{4(Z_{\alpha/2} + Z_{\beta})^2}{(\ln HR)^2}

Sample size:

n=dPeventn = \frac{d}{P_{event}}

Where:

  • d = number of events required
  • HR = hazard ratio
  • PeventP_{event} = probability of event
  • Zα/2Z_{\alpha/2} = Z-score for significance level
  • ZβZ_{\beta} = Z-score for power