Adjust base weights by the panel-selection probability (CEPAL ch. XVI)

Divides each incoming weight by Pr(panel selection) – the probability that a rotation panel belongs to the combined-wave sample – turning the design weight of the reference wave into the panel base weight of the longitudinal sample (d_base = d1 / Pr). This is the first step of the Verma-Betti-Ghellini longitudinal-weight sequence: combining k waves in a design that keeps g of its G rotation groups in all of them gives Pr = g / G, so the factor is its reciprocal (e.g. 4/3 when 3 of 4 groups persist, 4 when only 1 does).

Usage

step_panel_overlap(spec, prob, id = NULL)

Arguments

spec: a weighting_spec.
prob: a panel-selection probability in (0, 1]: an unquoted per-unit column/expression, or a single constant (e.g. panel_pr(pd, c("T1","T2"))).
id: optional string identifier for the step, shown in the recipe print-out and usable in collect_step_detail().

Value

The input weighting_spec with this step appended to its recipe.

Details

prob is a probability in (0, 1]: either a per-unit column (or expression) or a single constant applied to every active unit. When the data has a rotation_group, get the constant from panel_pr(): prob = panel_pr(pd, c("T1", "T2")). When it does not (e.g. the Chilean ENE), derive the probability yourself (from the design fraction or the cluster) and pass it here. Run this on the longitudinal sample (the intersection of the combined waves), before the attrition and calibration steps.

Examples

# wide longitudinal file of the units in sample in both waves
wide <- panel_merge(
  list(T1 = subset(panel_ine, ola == 1), T2 = subset(panel_ine, ola == 2)),
  by = c("id_hogar", "nper"), require = "all")

# rotation group known -> derive Pr(panel selection) from the panel design
pd <- panel_design(panel_ine, unit = c("id_hogar", "nper"), wave = "ola",
                   rotation_group = "grupo_rotacion")
weighting_spec(wide, base_weights = w_base_T1) |>
  step_panel_overlap(prob = panel_pr(pd, c("1", "2"))) |> prep()
#> 
#> == Weighting specification (weightflow) ==
#> Data    : 1717 cases
#> Base wts: w_base_T1
#> Steps   :
#>   1. panel overlap  [panel_overlap_1]
#> Status  : estimated (prep)
#> 
#> Stage summary:
#>                       stage n_active sum_wts cv_wts deff_kish n_eff
#>                        base     1717  245498    0.3      1.09  1575
#>  stage_1_step_panel_overlap     1717  294597    0.3      1.09  1575
#> 
#> 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.
#> 

# no rotation group (e.g. Chile ENE) -> pass the probability directly
weighting_spec(wide, base_weights = w_base_T1) |>
  step_panel_overlap(prob = 5 / 6) |> prep()
#> 
#> == Weighting specification (weightflow) ==
#> Data    : 1717 cases
#> Base wts: w_base_T1
#> Steps   :
#>   1. panel overlap  [panel_overlap_1]
#> Status  : estimated (prep)
#> 
#> Stage summary:
#>                       stage n_active sum_wts cv_wts deff_kish n_eff
#>                        base     1717  245498    0.3      1.09  1575
#>  stage_1_step_panel_overlap     1717  294597    0.3      1.09  1575
#> 
#> 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.
#>