PLANVARS Subcommand (CSPLAN command)

PLANVARS is used to name planwise variables to be created when a sample is extracted or used as input to the selection or estimation process.

ANALYSISWEIGHT. Final sample weights for each unit to be used by Complex Samples analysis procedures in the estimation process. ANALYSISWEIGHT is required if an analysis design is specified. It is ignored with a warning if a sample design is specified.

SAMPLEWEIGHT. Overall sample weights that will be generated when the sample design is executed using CSSELECT. A final sampling weight is created automatically when the sample plan is executed.

• SAMPLEWEIGHT is honored only if a sampling design is specified. It is ignored with a warning if an analysis design is specified.
• Sample weights are positive for selected units. They take into account all stages of the design as well as previous sampling weights if specified.
• If SAMPLEWEIGHT is not specified, a default name (SampleWeight_Final_) is used for the sample weight variable.

PREVIOUSWEIGHT. Weights to be used in computing final sampling weights in a multistage design.

PREVIOUSWEIGHT is honored only if a sampling design is specified. It is ignored with a warning if an analysis design is specified.

Typically, the previous weight variable is produced in an earlier stage of a stage-by-stage sample selection process. CSSELECT multiplies previous weights with those for the current stage to obtain final sampling weights.

For example, suppose that you want to sample individuals within cities but only city data are available at the outset of the study. For the first stage of extraction, a design plan is created that specifies that 10 cities are to be sampled from the active file. The PLANVARS subcommand specifies that sampling weights are to be saved under the name CityWeights.

CSPLAN SAMPLE   
  /PLAN FILE='/survey/city.csplan'
  /PLANVARS SAMPLEWEIGHT=CityWeights
  /DESIGN CLUSTER=city
  /METHOD TYPE=PPS_WOR
  /MOS VARIABLE=SizeVar
  /SIZE VALUE=10.

This plan would be executed using CSSELECT on an active file in which each case is a city.

For the next stage of extraction, a design plan is created that specifies that 50 individuals are to be sampled within cities. The design uses the PREVIOUSWEIGHT keyword to specify that sample weights generated in the first stage are to be used when computing final sampling weights for selected individuals. Final weights are saved to the variable FinalWeights.

CSPLAN SAMPLE
  /PLAN FILE='/survey/individuals.csplan'
  /PLANVARS PREVIOUSWEIGHT=CityWeights
            SAMPLEWEIGHT=FinalWeights
  /DESIGN STRATA=city
  /METHOD TYPE=SIMPLE_WOR
  /SIZE VALUE=50.

The plan for stage 2 would be executed using CSSELECT on an active file in which cases represent individuals and both city and CityWeights are recorded for each individual. Note that city is identified as a stratification variable in this stage, so individuals are sampled within cities.