Survival Power Analysis - Distribution Support Module — .get_weibull

Enhanced distribution support for survivalPower function Implements Weibull, log-normal, and piecewise exponential distributions

Usage

.get_weibull_parameters(median_survival, shape)

Arguments

median_survival: Median survival time
shape: Weibull shape parameter (gamma)

Value

List with lambda (scale) and shape parameters

Details

For Weibull distribution: S(t) = exp(-(lambda*t)^shape) Median: m = (log(2)/lambda)^(1/shape) Therefore: lambda = (log(2)/m)^(1/shape)

References

Lachin, J. M., & Foulkes, M. A. (1986). Evaluation of sample size and power for analyses of survival with allowance for nonuniform patient entry, losses to follow-up, noncompliance, and stratification. Biometrics, 42(3), 507-519. PMID: 3567285 Calculate Weibull distribution parameters from median survival