INCLPROB Subcommand (CSPLAN command)

The INCLPROB subcommand specifies the proportion of units drawn from the population at a given stage. Specify a single value, a variable name, or a matrix of inclusion probabilities for design strata.

  • The POPSIZE and INCLPROB subcommands are mutually exclusive. An error occurs if both are specified for a particular stage.
  • Proportions must be a positive value less than or equal to 1.

VALUE. Apply a single value to all strata. For example, VALUE=0.10 indicates that 10% of elements in each stratum were selected.

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

For example, the following syntax indicates that 10% of units were selected from the North stratum and 20% were selected from the South stratum:

/INCLPROB MATRIX=region;  'North' 0.1; 'South' 0.2

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

/INCLPROB MATRIX=region sex; 'North' 'Male' 0.1; 'North' 'Female' 0.15; 
                             'South' 'Male' 0.24; 'South' 'Female' 0.3
  • 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 proportion specification must contain one category value per variable. If multiple proportions 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 proportion specification. The semicolon is not allowed after the last proportion specification.

VARIABLE. Specify the name of a single variable that contains inclusion probabilities.