plot_posterior {abtest}

Plot Posterior

Description

Function for plotting the posterior distribution.

Usage

plot_posterior(
  x,
  what = "logor",
  hypothesis = "H1",
  ci = 0.95,
  p1lab = "p1",
  p2lab = "p2",
  p1adj = 0.44,
  p2adj = 0.56,
  ...
)

Arguments

x

object of class "ab".

what

character specifying for which quantity the posterior should be plotted. Either "logor" (i.e., log odds ratio) , "or" (i.e., odds ratio), "p1p2" (i.e., the marginal posteriors of the latent "success" probabilities in the experimental and control condition), "rrisk" (i.e., relative risk, the ratio of the "success" probability in the experimental and the control condition), or "arisk" (i.e., absolute risk, the difference of the "success" probability in the experimental and control condition).

hypothesis

character specifying whether to plot the two-sided posterior distribution (i.e., "H1"), the one-sided posterior distribution with lower truncation point (i.e., "H+"), or the one-sided posterior distribution with upper truncation point (i.e., "H-").

ci

numeric value specifying the ci% central credible interval. The default is 0.95 which yields a 95% central credible interval.

p1lab

determines p1 x-axis label. Only relevant for what = "p1p2".

p2lab

determines p2 x-axis label. Only relevant for what = "p1p2".

p1adj

determines p1 x-axis label adjustment. Only relevant for what = "p1p2".

p2adj

determines p2 x-axis label adjustment. Only relevant for what = "p1p2".

...

further arguments

Details

The resulting plot displays the posterior density for the quantitiy of interest and also displays the corresponding prior density. The values of the posterior median and a ci% central credible interval are displayed on top of the plot.

Author(s)

Quentin F. Gronau

Examples

# synthetic data
data <- list(y1 = 10, n1 = 28, y2 = 14, n2 = 26)

# Bayesian A/B test with default settings
ab <- ab_test(data = data, posterior = TRUE)

# plot parameter posterior
plot_posterior(x = ab, what = "logor")
plot_posterior(x = ab, what = "or")
plot_posterior(x = ab, what = "p1p2")
plot_posterior(x = ab, what = "rrisk")
plot_posterior(x = ab, what = "arisk")


# example of good width and height values for saving to file
cairo_pdf(file.path(tempdir(), "test_plot.pdf"),
          width = 530 / 72, height = 400 / 72)
plot_posterior(ab, what = "p1p2")
dev.off()