Outputs a table of important synthetic controls and their corresponding weights, sorted by weight. The table is truncated to exclude synthetic controls that do not matter for any estimate — for each estimate, the truncated controls may have total weight no larger that 1-mass.

Usage

synthdid_controls(
  estimates,
  sort.by = 1,
  mass = SYNTHDID_CONTROLS_MASS_DEFAULT,
  weight.type = "omega"
)

Arguments

estimates,: a list of estimates output by synthdid_estimate. Or a single estimate.
sort.by,: the index of the estimate to sort by. Defaults to 1.
mass,: which controls the length of the table. Defaults to 0.9.
weight.type,: 'omega' for units, 'lambda' for time periods

Value

A matrix of weights for the top controls/periods, sorted by importance.

Examples

# \donttest{
data(california_prop99)
setup <- panel.matrices(california_prop99)
tau.hat <- synthdid_estimate(setup$Y, setup$N0, setup$T0)

# Show top control units
synthdid_controls(tau.hat, weight.type = "omega")
#>                    Weight
#> Nevada         0.12448923
#> New Hampshire  0.10504758
#> Connecticut    0.07828729
#> Delaware       0.07036812
#> Colorado       0.05751279
#> Illinois       0.05338782
#> Nebraska       0.04785319
#> Montana        0.04513521
#> Utah           0.04151766
#> New Mexico     0.04056827
#> Minnesota      0.03949464
#> Wisconsin      0.03666708
#> West Virginia  0.03356911
#> North Carolina 0.03280518
#> Idaho          0.03146821
#> Ohio           0.03146077
#> Maine          0.02821102
#> Iowa           0.02593863

# Show top time periods
synthdid_controls(tau.hat, weight.type = "lambda")
#>         Weight
#> 1988 0.4271072
#> 1986 0.3663560
#> 1987 0.2064182

# Compare multiple estimates
tau.sc <- sc_estimate(setup$Y, setup$N0, setup$T0)
synthdid_controls(list(sdid = tau.hat, sc = tau.sc))
#>                      sdid         sc
#> Nevada         0.12448923 0.20442613
#> New Hampshire  0.10504758 0.04536371
#> Connecticut    0.07828729 0.10446734
#> Delaware       0.07036812 0.00405026
#> Colorado       0.05751279 0.01331585
#> Illinois       0.05338782 0.00000000
#> Nebraska       0.04785319 0.00000000
#> Montana        0.04513521 0.23227270
#> Utah           0.04151766 0.39610401
#> New Mexico     0.04056827 0.00000000
#> Minnesota      0.03949464 0.00000000
#> Wisconsin      0.03666708 0.00000000
#> West Virginia  0.03356911 0.00000000
#> North Carolina 0.03280518 0.00000000
#> Idaho          0.03146821 0.00000000
#> Ohio           0.03146077 0.00000000
#> Maine          0.02821102 0.00000000
#> Iowa           0.02593863 0.00000000
# }