multifrailty: Formula Interface for Shared Frailty Regression Models

In MultiFrailty: Shared Frailty Regression Models with Inverse Gaussian, Generalized Lindley, and Gamma Frailty Distributions

Formula Interface for Shared Frailty Regression Models

Description

Fits shared frailty regression models using a formula specifying survival response (e.g., survival::Surv(time, status) ~ x1 + x2) and data frame.

Usage

multifrailty(
  formula,
  data,
  baseline = c("weibull", "gw"),
  frailty = c("none", "gamma", "ig", "gl1", "gl2"),
  method = "NR",
  ...
)

Arguments

formula	Model formula of the form survival::Surv(time, status) ~ x1 + x2.
data	Data frame containing variables in formula.
baseline	Character string specifying baseline hazard: "weibull" or "gw".
frailty	Character string specifying frailty family: "none", "gamma", "ig", "gl1", or "gl2".
method	Optimization method for maxLik: "NR" (Newton-Raphson) or "BFGS".
...	Additional arguments passed to fit_frailty.

Value

Object of class c("multifrailty", "multifrailty_fit").

References

Pandey, A., Hanagal, D. D., & Tyagi, S. (2022). Shared Frailty Models Based on Cancer Data. International Journal of Statistics and Reliability Engineering, 9(3), 461-474.

Pandey, A., & Tyagi, S. (2021). Comparison of Multiplicative Frailty Models Under Weibull Baseline Distribution. Lobachevskii Journal of Mathematics, 42(13), 3184-3195.

Examples

set.seed(123)
df <- data.frame(
  time = stats::rexp(50, rate = 0.1),
  status = sample(c(0, 1), 50, replace = TRUE),
  age = stats::rnorm(50, mean = 50, sd = 10),
  sex = sample(c(0, 1), 50, replace = TRUE)
)
fit <- multifrailty(survival::Surv(time, status) ~ age + sex, data = df,
                    baseline = "weibull", frailty = "gamma")
print(fit)

MultiFrailty documentation built on Aug. 8, 2026, 1:07 a.m.