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 |

`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 |

`nobs` |
Number of observations. |

`nvars` |
Number of covariates. |

`d` |
Vector of length |

`D` |
Matrix of size |

`B` |
Matrix of size |

### See Also

### 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))
```

*ahaz*version 1.15 Index]