ahaz.partial {ahaz} R Documentation

## Partial calculation of estimating quantities used by ahaz

### Description

Partial calculation of the quantities used in the estimating equations for ahaz.

### Usage

ahaz.partial(surv, X, weights, idx)


### Arguments

 surv Response in the form of a survival object, as returned by the function Surv() in the package survival. Right-censored and counting process format (left-truncation) is supported. Tied survival times are not supported. X Design matrix. Missing values are not supported. weights Optional vector of observation weights. Default is 1 for each observation. idx Vector of indices of covariates to use in the calculations.

### Details

The function is intended mainly for programming use when a very large number of covariates are considered and direct application of ahaz is unfeasible.

The estimating equations for the semiparametric additive hazards model are of the form D\beta=d with D a quadratic matrix with number of columns equal to the number of covariates. The present function returns d[idx], D[idx,], and B[idx,]; the latter a matrix such that D^{-1} B D^{-1} estimates the covariance matrix of the regression coefficients.

### Value

A list containing the following elements:

 call The call that produced this object. idx A copy of the argument idx. nobs Number of observations. nvars Number of covariates. d Vector of length length(idx). D Matrix of size length(idx) x nvars. B Matrix of size length(idx) x nvars.

ahaz, ahaz.adjust.

### Examples

data(sorlie)

# Break ties
set.seed(10101)
time <- sorlie$time+runif(nrow(sorlie))*1e-2 # Survival data + covariates surv <- Surv(time,sorlie$status)
X <- as.matrix(sorlie[,3:ncol(sorlie)])

# Get D for the first 10 covariates only
a<-ahaz.partial(surv,X,idx=1:10)
pD1 <- a$D # Equivalent to the (slower) solution b <- ahaz(surv,X) pD2 <- b$D[1:10,]
max(abs(pD1-pD2))



[Package ahaz version 1.15 Index]