Plot Prior and Posterior Distributions with Optional True Value

This function generates a density plot comparing the prior and posterior distributions of a parameter. An optional vertical dashed line can be added to indicate the true parameter value.

Usage

plot_prior_posterior(prior_values, posterior_values, true_value = NULL)

Arguments

prior_values

A numeric vector of samples from the prior distribution.

posterior_values

A numeric vector of samples from the posterior distribution.

true_value

Optional numeric value representing the true parameter value to be shown as a vertical dashed line.

Value

A ggplot2 object representing the density plot comparing the prior and posterior distributions.

Details

The function uses geom_density() to visualize both prior and posterior samples, and geom_vline() to optionally display the true parameter value. It uses theme_minimal() and places the legend at the bottom for clarity.

Examples

prior <- rnorm(1000, mean = 0, sd = 2)
posterior <- rnorm(1000, mean = 1, sd = 0.5)
true_value <- 1.2
plot_prior_posterior(prior, posterior, true_value)