NC coverage comparison figure

Produces a 4-panel figure comparing PGC2, PGC2Gm, and IV2SLS2 as negative-control coverage of each path's confounder composite (omega_1, omega_2) drops. This is the coverage-axis analogue of the instrument-violation degradation surface: it shows how bias accumulates as the proxy panel captures less of the confounder.

Usage

plot_nc_coverage_comparison(
  omega1_sweep,
  omega2_sweep,
  t1e_omega2 = NULL,
  file = NULL,
  width = 10,
  height = 12
)

Arguments

omega1_sweep

Summary from sweep_mediation_param("omega_1", ...): a list with $summary (columns param_value, method, NDE_bias, NIE_bias).

omega2_sweep

Same, sweeping omega_2.

t1e_omega2

Result of sweep_mediation_null_by_conf(...) run across an omega_2 grid: a data frame with columns omega_2, method, NIE_type1. If NULL, Panel D is omitted.

file

Optional file path to save the figure.

width

Figure width in inches.

height

Figure height in inches.

Value

A patchwork ggplot object.

Details

Panels: (A) NDE bias vs omega_1, (B) NIE bias vs omega_2, (C) NDE/NIE bias vs omega (both paths), (D) NIE Type I error vs omega_2.

Examples

# Toy sweeps standing in for sweep_mediation_param("omega_1"/"omega_2", ...)
mk <- function() {
  s <- expand.grid(param_value = c(0.3, 0.7),
    method = c("IV2SLS2", "PGC2", "PGC2Gm"))
  s$NDE_bias <- rnorm(nrow(s), 0, 0.05)
  s$NIE_bias <- rnorm(nrow(s), 0, 0.05)
  list(summary = s)
}
plot_nc_coverage_comparison(mk(), mk())