Drop ineligible (out-of-scope) units — step_drop

Sets the weight of known-ineligible units to zero so they leave the cascade (excluded from every later step and from collect_weights). No redistribution is done.

Usage

step_drop_ineligible(spec, ineligible)

Arguments

spec: a weighting_spec.
ineligible: a 0/1 dummy column (1 = ineligible) or any logical condition (unquoted) that is TRUE for out-of-scope units.

Details

Apply it AFTER step_unknown_eligibility: ineligibles must be present and NOT flagged as unknown during that step, so they take part in the known-eligibility group and receive their share of the redistributed unknown weight. Their weight is then correctly discarded here (it represents the ineligible share of the unknown units, which are out of scope).

Examples

df <- transform(sample_survey,
                ineligible = as.integer(region == "West" & age > 90))
weighting_spec(df, base_weights = pw) |>
  step_drop_ineligible(ineligible = ineligible) |>
  prep()
#> 
#> == Weighting specification (weightflow) ==
#> Data    : 467 cases
#> Base wts: pw
#> Steps   :
#>   1. drop ineligible
#> Status  : estimated (prep)
#> 
#> Stage summary:
#>                         stage n_active sum_wts cv_wts deff_kish n_eff
#>                          base      467    4371  0.236     1.056   442
#>  stage_1_step_drop_ineligible      466    4364  0.236     1.055   442
#> 
#> deff_kish = 1 + CV^2 (Kish design effect from unequal weighting);
#> n_eff = n_active / deff_kish. Both worsen with each adjustment and
#> improve with trimming.
#>