Cross-validated Z-residuals for Shared Frailty Cox Models — CV_Zresidual_coxph_frailty

Internal function to compute cross-validated Z-residuals for shared frailty Cox proportional hazards models.

Usage

CV_Zresidual_coxph_frailty_survival(
  fit.coxph,
  data,
  nfolds,
  foldlist,
  n.rep,
  ...
)

Arguments

fit.coxph: A fitted survival::coxph model object containing a frailty term.
data: Optional data frame containing the data. Required if the original model was fit without specifying the data argument or if foldlist is supplied.
nfolds: Integer. Number of folds for cross-validation (K in K-fold CV).
foldlist: Optional list specifying custom fold assignments.
n.rep: Integer. Number of repeated cross-validations.
...: Additional arguments.

Value

A matrix containing the cross-validated Z-residuals (\(N \times nrep\)) with diagnostic attributes: Survival.Prob, linear.pred, censored.status, covariates, and object.model.frame.

Details

This function implements the K-fold cross-validation procedure specifically for shared frailty Cox models (i.e., those containing a frailty() term). In each fold, the model is refitted on the training data, and the Z-residuals are calculated on the held-out test data.