The VARIANCE group in SURVIVAL consists of the beta estimates,
their variance-covariance matrix under the user specified sample design
(DESIGN option), the SRS variance-covariance
matrix, the idempotent matrix required for hypothesis testing, and denominator
degrees of freedom. This group is not printed by default, though the statistics
are available for individual printing, either by explicit use of appropriate
keyword(s) on the PRINT statement
or by specifying VARIANCE=DEFAULT or VARIANCE=ALL on the PRINT
statement. The keywords in the VARIANCE group are listed below in default
order.