RATE Subcommand (CSPLAN command)

The RATE subcommand specifies the percentage of units to draw at the current stage—that is, the sampling fraction.

  • Specify a single value, a variable name, or a matrix of rates for design strata. In all cases, the value 1 is treated as 100%.
  • Rate values must be positive.
  • RATE is ignored with a warning if the PPS_MURTHY or PPS_BREWER method is specified.
  • Either SIZE or RATE must be specified for each stage. An error occurs if both are specified.

VALUE. Apply a single value to all strata. For example, VALUE=.10 selects 10% of units per stratum.

MATRIX. Specify disproportionate rates for different strata. Specify one or more variables after the MATRIX keyword. Then provide one rate specification per stratum. A rate specification includes a set of category values and a rate value. Category values should be listed in the same order as variables to which they apply. Semicolons are used to separate the rate specifications.

For example, the following syntax selects 10% of units from the North stratum and 20% from the South stratum:

/RATE MATRIX=region;  'North' .1; 'South' .2

If there is more than one variable, specify one rate per combination of strata. For example, the following syntax specifies rate values for combinations of Region and Sex strata:

/RATE MATRIX=region sex; 'North' 'Male' .1; 'North' 'Female' .15; 
                         'South' 'Male' .24; 'South' 'Female' .3
  • The variable list must contain all or a subset of stratification variables from the same and previous stages and cluster variables from the previous stages. An error occurs if the list contains variables that are not defined as strata or cluster variables.
  • Each rate specification must contain one category value per variable. If multiple rate specifications are provided for the same strata or combination of strata, only the last one is honored.
  • String and date category values must be quoted. A semicolon must appear after the variable list and after each rate specification.
  • The semicolon is not allowed after the last rate specification.

VARIABLE. Specify the name of a single variable that contains the sample rates.