METHOD Subcommand (CSPLAN command)

The METHOD subcommand specifies the sample extraction method. A variety of equal- and unequal-probability methods are available.

The following table lists extraction methods and their availability at each stage of the design. For details on each method, see the CSSELECT algorithms document.

  • PPS methods are available only in stage 1. WR methods are available only in the final stage. Other methods are available in any stage.
  • If a PPS method is chosen, a measure of size (MOS) must be specified.
  • If the PPS_WOR, PPS_BREWER, PPS_SAMPFORD, or PPS_MURTHY method is selected, first-stage joint inclusion probabilities are written to an external file when the sample plan is executed. Joint probabilities are needed for UNEQUAL_WOR estimation by Complex Samples analysis procedures.
  • By default, CSPLAN chooses an appropriate estimation method for the selected sampling method. If ESTIMATION=WR, Complex Samples analysis procedures use the WR (with replacement) estimator regardless of the sampling method.
Type Description Default estimator
SIMPLE_WOR Selects units with equal probability. Units are extracted without replacement. EQUAL_WOR
SIMPLE_WR Selects units with equal probability. Units are extracted with replacement. WR
SIMPLE_SYSTEMATIC Selects units at a fixed interval throughout the sampling frame or stratum. A random starting point is chosen within the first interval. WR
SIMPLE_CHROMY Selects units sequentially with equal probability. Units are extracted without replacement. WR
PPS_WOR Selects units with probability proportional to size. Units are extracted without replacement. UNEQUAL_WOR
PPS_WR Selects units with probability proportional to size. Units are extracted with replacement. WR
PPS_SYSTEMATIC Selects units by systematic random sampling with probability proportional to size. Units are extracted without replacement. WR
PPS_CHROMY Selects units sequentially with probability proportional to size without replacement. WR
PPS_BREWER Selects two units from each stratum with probability proportional to size. Units are extracted without replacement. UNEQUAL_WOR
PPS_MURTHY Selects two units from each stratum with probability proportional to size. Units are extracted without replacement.

 UNEQUAL_WOR
PPS_SAMPFORD An extension of the Brewer's method that selects more than two units from each stratum with probability proportional to size. Units are extracted without replacement. UNEQUAL_WOR