Compute Hazard Ratio for a Single Subgroup

Internal helper function to compute HR and CI for a subgroup. Uses robust (sandwich) standard errors for consistency with cox_summary().

Usage

compute_sg_hr(
  df,
  sg_name,
  outcome.name,
  event.name,
  treat.name,
  E.name,
  C.name,
  z_alpha = qnorm(0.975),
  conf.level = 0.95
)

Arguments

df

Data frame for the subgroup.

sg_name

Character. Name of the subgroup.

outcome.name

Character. Name of survival time variable.

event.name

Character. Name of event indicator variable.

treat.name

Character. Name of treatment variable.

E.name

Character. Label for experimental arm.

C.name

Character. Label for control arm.

z_alpha

Numeric. Z-multiplier for CI (default: qnorm(0.975) for 95% CI).

conf.level

Numeric. Confidence level for intervals (default: 0.95).

Value

Data frame with single row of HR estimates, or NULL if model fails.