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SPSS® 12.0 Command Syntax Reference

SPSS® 12.0 Command Syntax Reference

SPSS® 12.0 Command Syntax Reference

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794 KM<br />

Example<br />

KM LENGTH BY SEXRACE<br />

/STATUS=EMPLOY EVENT (1) LOST (3,5 THRU 8)<br />

/STRATA=LOCATION<br />

/TEST = BRESLOW<br />

/COMPARE = PAIRWISE.<br />

• TEST specifies the Breslow test.<br />

• COMPARE uses the Breslow test statistic to compare all distinct pairs of SEXRACE values<br />

and pools the test results over all strata defined by LOCATION.<br />

• Test statistics are displayed at the end of output for all strata.<br />

TREND Subcommand<br />

TREND specifies that there is a trend across factor levels. This information is used when computing<br />

the tests for equality of survival functions specified on the TEST subcommand.<br />

• The minimum specification is the subcommand keyword by itself. The default metric is<br />

chosen as follows:<br />

if g is even,<br />

( – ( g – 1)<br />

, …, – 3,<br />

– 1,<br />

1, 3, …, ( g – 1)<br />

)<br />

otherwise,<br />

( g – 1)<br />

g 1<br />

– ---------------- … – 1 0 1 …<br />

2<br />

–<br />

⎛ ( )<br />

, , , , , , ---------------- ⎞<br />

⎝ 2 ⎠<br />

where g is the number of levels for the factor variable.<br />

• If TREND is specified but COMPARE is not, KM performs the default log rank test with the<br />

trend metric for an OVERALL POOLED comparison.<br />

• If the metric specified on TREND is longer than required by the factor levels, KM displays<br />

a warning and ignores extra values.<br />

Example<br />

KM LENGTH BY SEXRACE<br />

/STATUS=EMPLOY EVENT (1) LOST (3,5 THRU 8)<br />

/STRATA=LOCATION<br />

/TREND.<br />

• TREND is specified by itself. KM uses the default metric. Since SEXRACE has four levels,<br />

the default is (–3,–1, 1, 3).<br />

• Even though no TEST or COMPARE subcommand is specified, KM performs the default<br />

log rank test with the trend metric and does a default OVERALL POOLED comparison.

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