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Plot differences between mediation effects

Source: R/plot-effects.R
plot_contrasts.Rd

Draw contrast estimates and their confidence intervals relative to zero. With a moderator, contrasts compare groups or stored moderator levels within each effect. Without a moderator, specific indirect paths are compared with one another. The displayed subtraction order is explicit.

Usage

plot_contrasts(
  result,
  paths = NULL,
  type = c("indirect", "paths", "overall"),
  contrasts = NULL,
  standardized = FALSE,
  engine = c("mc", "boot"),
  labels = NULL,
  title = NULL,
  x_label = NULL,
  y_label = NULL,
  base_size = 12,
  ncol = NULL
)

Arguments

result

A result returned by wsMed().

paths

Optional character vector of effect identifiers, in display order. NULL selects all available effects. Both indirect_1 and indirect_effect_1 are accepted when they identify an available effect.

type

"indirect" for specific indirect effects, "paths" for available conditional path coefficients, or "overall" for total indirect and total effects.

contrasts

Optional exact contrast labels to select, in display order. NULL selects all. Inspect the corresponding result table or the returned plot's data$Contrast for available labels.

standardized

Use standardized results, requested when fitting with standardized = TRUE. No scaling is recomputed from interval endpoints.

engine

For ci_method = "both", select "mc" or "boot". For a single engine its stored results are used.

labels

Optional named character vector mapping effect identifiers to display labels. Partial mappings are allowed.

title

Optional plot title.

x_label, y_label

Optional axis labels.

base_size

Base font size.

ncol

Optional number of facet columns.

Value

A ggplot object with plotted data and a wsmed_plot attribute.

Details

Moderator contrasts use the existing joint-draw contrast tables. Without a moderator, only type = "indirect" is available: contrasts are computed from the stored joint draws, with point estimates evaluated at fitted/pooled parameters. Their intervals are percentile intervals. Standardized draws use the same draw-specific marginal endpoint scales as other standardized effects. No model is refitted. Interval endpoints for two separate effects are never subtracted to construct a contrast CI. paths and labels apply to effect panels when a moderator is present; without a moderator, paths selects the indirect effects to compare and labels maps the full contrast labels. Continuous overall contrasts are unavailable when the fitted result does not contain that contrast table.

See also

plot_effects(), plot_conditional_effects()