SurvS4: Create a Survival Object

Description

Create a survival object, usually used as a response variable in a model formula.

Usage

SurvS4(time, time2, event, type =, origin = 0)
is.SurvS4(x)

Arguments

time

for right censored data, this is the follow up time. For interval data, the first argument is the starting time for the interval.

any R object.

event

The status indicator, normally 0=alive, 1=dead. Other choices are TRUE/FALSE (TRUE = death) or 1/2 (2=death). For interval censored data, the status indicator is 0=right censored, 1=event at time

time2

ending time of the interval for interval censored  or counting
    process data only.  Intervals are assumed to be open on the left and
    closed on the right, (start, end].  For counting process
    data, event indicates whethe

type

character string specifying the type of censoring. Possible values
    are "right", "left", "counting",
    "interval", or "interval2".  The default is
    "right" or "cou

origin

for counting process data, the hazard function origin.  This is most
    often used in conjunction with a model containing time dependent
    strata in order to align the subjects properly when they cross over
    from one strata to another.

`Value`

An object of class SurvS4 (formerly Surv).
  There are methods for print, is.na, and
  subscripting survival objects. SurvS4 objects are
  implemented as a matrix of 2 or 3 columns.
  In the case of is.SurvS4, a logical value
  TRUE if x inherits from class
  "SurvS4", otherwise a FALSE.

`Details`

Typical usages are
SurvS4(time, event)
SurvS4(time, time2, event, type=, origin=0)

In theory it is possible to represent interval censored
data without a third column containing the explicit status.
Exact, right censored, left censored and interval censored
observation would be represented as intervals of (a,a),
(a, infinity), (-infinity,b), and (a,b) respectively; each
specifying the interval within which the event is known to
have occurred.

If type = "interval2" then the representation given
above is assumed, with NA taking the place of infinity.
If `type="interval" event must be given.
If event is 0, 1, or 2,
the relevant information is assumed to be contained in
time, the value in time2 is ignored, and the
second column of the result will contain a placeholder.

Presently, the only methods allowing interval
censored data are the parametric models computed by
survreg, so the distinction between
open and closed intervals is unimportant.  The distinction
is important for counting process data and the Cox model.

The function tries to distinguish between the use of 0/1
and 1/2 coding for left and right censored data using
if (max(status)==2).  If 1/2 coding is used and all
the subjects are censored, it will guess wrong.  Use 0/1
coding in this case.

`See Also`

SurvS4-class,
  cenpoisson,
  survreg,
  leukemia.

`Examples`

Run this codewith(leukemia, SurvS4(time, status))
class(with(leukemia, SurvS4(time, status)))
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