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 |