Restricted mean survival time (RMST) from an exnex_surv fit

Computes the restricted mean survival time up to a horizon `tmax`: $$RMST(tmax) = \int_0^{tmax} S(t)\,dt.$$ The integral is evaluated numerically (trapezoidal rule over a fine grid) for every posterior draw, then summarised with posterior quantiles.

Usage

rmst(fit, tmax = NULL, newdata = NULL, level = 0.95, grid_points = 400, ...)

Arguments

fit

A fitted `exnex_surv` object.

tmax

A positive scalar horizon up to which the RMST is computed. Defaults to `max(fit$data$time)`.

newdata

Optional data frame (one row gives one RMST).

level

Credible-interval level (default `0.95`).

grid_points

Resolution of the numerical quadrature (default `400`).

...

Unused.

Value

A `data.frame` with columns `group`, `rmst`, `lower`, `upper`.