STRATA Subcommand (KM command)

STRATA identifies a stratification variable—that is, a variable whose values are used to form subgroups (strata) within the categories of the factor variable. Analysis is done within each level of the strata variable for each factor level, and estimates are pooled over strata for an overall comparison of factor levels.

  • The minimum specification is the subcommand keyword with one, and only one, variable name.
  • If you have more than one strata variable, create a new variable to combine the levels on separate variables before invoking the KM command.
  • There is no limit to the number of levels for the strata variable.

Example

KM LENGTH BY SEXRACE
 /STATUS=EMPLOY EVENT (1) LOST (3,5 THRU 8)
 /STRATA=LOCATION.
  • STRATA specifies LOCATION as the stratification variable. Analysis of the length of unemployment is done for each location within each sex and race subgroup.