SPSS® 12.0 Command Syntax Reference

1550 SURVIVAL
• INTERVALS produces life tables computed from 0 to 12 months at one-month intervals
and from 13 to 24 months at three-month intervals.
Example
SURVIVAL ONSSURV BY TREATMNT (1,3)
/STATUS = OUTCOME (3,4) FOR ONSSURV
/INTERVALS = THRU 50 BY 6.
• On the INTERVALS subcommand, the value following BY (6) does not divide evenly into
the period to which it applies (50). Thus, the endpoint of the period is adjusted upward to
the next even multiple of the BY value, resulting in a period of 54 with 9 intervals of 6
units each.
Example
SURVIVAL ONSSURV BY TREATMNT (1,3)
/STATUS = OUTCOME (3,4) FOR ONSSURV
/INTERVALS = THRU 50 BY 6 THRU 100 BY 10 THRU 200 BY 20.
• Multiple THRU and BY specifications are used on the INTERVAL subcommand to divide
the period of time under examination into intervals of different lengths.
• The first THRU and BY specifications are adjusted to produce even intervals as in the
previous example. As a result, the following THRU and BY specifications are automatically
readjusted to generate 5 intervals of 10 units (through 104), followed by 5 intervals
of 20 units (through 204).
STATUS Subcommand
To determine whether the terminal event has occurred for a particular observation, SURVIVAL
checks the value of a status variable. STATUS lists the status variable associated with each
survival variable and the codes that indicate that a terminal event occurred.
• Specify a status variable followed by a value range enclosed in parentheses. The value
range identifies the codes that indicate that the terminal event has taken place. All
cases with non-negative times that do not have a code in the value range are classified
as censored cases, which are cases for which the terminal event has not yet occurred.
• If the status variable does not apply to all the survival variables, specify FOR and the name
of the survival variable(s) to which the status variable applies.
• Each survival variable on TABLES must have an associated status variable identified by a
STATUS subcommand.
• Only one status variable can be listed on each STATUS subcommand. To specify multiple
status variables, use multiple STATUS subcommands.
• If FOR is omitted on the STATUS specification, the status-variable specification applies to
all of the survival variables not named on another STATUS subcommand.
• If more than one STATUS subcommand omits the keyword FOR, the final STATUS
subcommand without FOR applies to all survival variables not specified by FOR on other
STATUS subcommands. No warning is printed.