gehan_heller_estimation {aftsem}R Documentation

Gehan-Heller Estimation of regression parameters

Description

Gehan-Heller Estimation of regression parameters

Usage

gehan_heller_estimation(
  y,
  Z,
  delta,
  binit,
  optimx.alg,
  variance.estimation,
  use.grad
)

Arguments

y

Numeric vector of survival times or times to event/censoring.

Z

Numeric matrix of covariates with observations in rows and covariates in columns.

delta

Numeric vector indicating censoring, with 1 for an event and 0 for censored observations.

binit

Numeric vector or matrix for initial estimates of regression coefficients.

optimx.alg

Optimalization algorithm that will be used (see optimx package documentation for more information)

variance.estimation

If covariance matrix will be estimated

use.grad

Indicator wheter numerical or excact gradient will be used, default is FALSE == numerical

Covariance estimation is programmed but not tested!

Value

A list containing the estimated regression coefficients ('BETA'), residuals ('RESID'), and the number of iterations taken by the optimization routine ('ITERS').

Note

The recommend use is with numerical aproximation of gradient. The true gradiet can be sensitive for initial beta values (binit). For Covariance estimation please set the variance.estimation in control list to TRUE.


[Package aftsem version 1.0 Index]