This class of objects is returned by the `coxph`

class of functions
to represent a fitted proportional hazards model.
Objects of this class have methods for the functions `print`

,
`summary`

, `residuals`

, `predict`

and `survfit`

.

The following components must be included in a legitimate `coxph`

object.

- coefficients
the vector of coefficients. If the model is over-determined there will be missing values in the vector corresponding to the redundant columns in the model matrix.

- var
the variance matrix of the coefficients. Rows and columns corresponding to any missing coefficients are set to zero.

- naive.var
this component will be present only if the

`robust`

option was true. If so, the`var`

component will contain the robust estimate of variance, and this component will contain the ordinary estimate. (A far better name would be`asymp.var`

since it contains the model-based asympotitic variance estimate, which is not necessarily "naive"; but that ship has sailed.)- loglik
a vector of length 2 containing the log-likelihood with the initial values and with the final values of the coefficients.

- score
value of the efficient score test, at the initial value of the coefficients.

- rscore
the robust log-rank statistic, if a robust variance was requested.

- wald.test
the Wald test of whether the final coefficients differ from the initial values.

- iter
number of iterations used.

- linear.predictors
the vector of linear predictors, one per subject. Note that this vector has been centered, see

`predict.coxph`

for more details.- residuals
the martingale residuals.

- means
vector of values used as the reference for each covariate. For instance, a later call to

`predict(fit, type='risk')`

will give the hazard ratio between an observation and this reference. (For most covariates this will contain the mean.)- n
the number of observations used in the fit.

- nevent
the number of events (usually deaths) used in the fit.

- concordance
a vector of length 6, containing the number of pairs that are concordant, discordant, tied on x, tied on y, and tied on both, followed by the standard error of the concordance statistic.

- first
the first derivative vector at the solution.

- weights
the vector of case weights, if one was used.

- method
the method used for handling tied survival times.

- na.action
the na.action attribute, if any, that was returned by the

`na.action`

routine.- timefix
the value of the timefix option used in the fit

- ...
The object will also contain the following, for documentation see the

`lm`

object:`terms`

,`assign`

,`formula`

,`call`

, and, optionally,`x`

,`y`

, and/or`frame`

.

`coxph`

, `coxph.detail`

, `cox.zph`

, `residuals.coxph`

, `survfit`

, `survreg`

.