survfit.object           package:survival           R Documentation

Survival Curve Object

Description:

     This class of objects is returned by the 'survfit' class of
     functions to represent a fitted survival curve. 

     Objects of this class have methods for the functions 'print',
     'summary', 'plot', 'points' and 'lines'. The 'print.survfit'
     method does more computation than is typical for a print method
     and is documented on a separate page.

COMPONENTS:

     The following components must be included in a legitimate
     'survfit' object.

     time the time points at which the curve has a step.

     n.risk the number of subjects at risk at t.

     n.event the number of events that occur at time t.

     surv the estimate of survival at time t+0. This may be a vector or
          a matrix.

     strata if there are multiple curves, this component gives the
          number of elements of the 'time' etc. vectors corresponding
          to the first curve, the second curve, and so on.  The names
          of the elements are labels for the curves.

     std.err the standard error of the cumulative hazard or
          -log(survival).

     upper upper confidence limit for the survival curve.

     lower lower confidence limit for the survival curve.

     conf.type the approximation used to compute the confidence limits.

     conf.int the level of the confidence limits, e.g. 90 or 95%.

     na.action the returned value from the na.action function, if any. 
          It will be used in the printout of the curve, e.g., the
          number of observations deleted due to missing values.

     call the call that produced the object.

SUBSCRIPTS:

     Survfit objects that contain multiple survival curves can be
     subscripted. This is most often used to plot a subset of the
     curves. Usually a single subscript will be used.  In one
     particular case - survival curves for multiple covariate values,
     from a Cox model that includes a 'strata' statement - there is a
     matrix of curves and 2 subscripts may be used. (In this case
     'summary.survfit' will also print the data as a matrix).

See Also:

     'survfit', 'plot.survfit', 'summary.survfit', 'print.survfit'.

