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Introduction

Introduction.Rmd

The purpose of BetaBase is to provide functions for estimating and visualizing beta distributions, commonly used for Bayesian inference of probabilities. Functions are provided to:

  • Determine the bounds of a credible interval containing a specified percent of the probability.
  • Calculate the expectation of a beta distribution from its parameters.
  • Determine the expected width of a confidence interval based on sample size.
  • Estimate the parameters of a beta distribution from quantiles.
  • Plot a beta distribution with optional interval shading and line indicating expected value.
  • ggplot2 geoms for interval shading and line indicating expected value.

This introduction is intended to demonstrate the use of a few functions without going into detail about options. For more details see articles/vignettes for specific functions or function documentation.

Plotting a beta Beta(6, 4) distribution.

plotdbeta(6, 4, expectation = TRUE, HDImass = 0.95)

Estimating beta parameters from quantiles.

betaParamsFromQuantiles(q = c(0.1, 0.7))
#> $a
#> [1] 3.078885
#> 
#> $b
#> [1] 5.224029

Estimating width of confidence interval from sample size (and other parameters)

df <- betaHDIwidthSim(genPriorMean = 0.1, genPriorN = 2)
ggplot(df, aes(n, HDIwidth)) +
  geom_path()