Plot the posterior distributions of marginal contrasts — plot_posterior

This function creates a plot of the posterior distributions of marginal contrasts obtained from a Bayesian model. It visualizes the distributions of the contrasts along with the Region of Practical Equivalence (ROPE) indicated by dashed lines. The plot uses ggplot2 and ggdist for visualization and is customizable with various parameters.

Usage

plot_posterior_contrasts(
  contrasts,
  model,
  dot_size = 0.1,
  slab_alpha = 0.3,
  scale_colours = c(viridis::viridis(100)[55], viridis::viridis(100)[5]),
  x_lab = "Effect size",
  base_size = 7,
  rope_txt = 1.5,
  ...
)

Arguments

contrasts: A marginaleffects object obtained with marginaleffects::comparisons() containing the contrasts to plot.
model: A fitted Bayesian model object (e.g., brmsfit) used to determine the ROPE range.
dot_size: Size of the dots representing the medians of posterior draws. Default is 0.1.
slab_alpha: Alpha transparency for the slab (density) of the posterior distributions.
scale_colours: A vector of two colours for the fill scale, where the first colour represents draws within the ROPE and the second colour represents draws outside the ROPE. Default uses viridis colours.
x_lab: Label for the x-axis. Default is "Effect size".
base_size: Base font size for the plot theme. Default is 7.
rope_txt: Size of the ROPE text annotation. Default is 1.5.
...: Additional arguments passed to the theme_pdf() function for further customization of the plot theme.

Value

A ggplot2 object representing the posterior contrasts plot.